Timothy A. Springer

The novel S527F mutation in the integrin beta3 chain induces a high affinity alphaIIbbeta3 receptor by hindering adoption of the bent conformation (2009)

Melchior, Chantal, Plançon, Sebastien, Margue, Christiane, ...

Three heterozygous mutations were identified in the genes encoding platelet integrin receptor alphaIIbbeta3 in a patient with an ill defined platelet disorder: one in the beta3 gene (S527F) and two...

A Specific Interface between Integrin Transmembrane Helices and Affinity for Ligand (2004)

Bing-Hao Luo, Timothy A. Springer, Junichi Takagi

Integrin receptors mediate cell-matrix interactions by altering the conformation of their intra- and extra- cellular domains, a process mediated by lateral separation of the transmembrane helices.

A Specific Interface between Integrin Transmembrane Helices and Affinity for Ligand (2004)

Bing-Hao Luo, Timothy A. Springer, Junichi Takagi

Conformational communication across the plasma membrane between the extracellular and intracellular domains of integrins is beginning to be defined by structural work on both domains. However, the...

A Partial Genomic DNA Clone for the alpha Subunit of the Mouse Complement Receptor Type 3 and Cellular Adhesion Molecule Mac-1 (1986)

Sastre, Leandro, Roman, Janet M., Teplow, David B., Dreyer, William J., Gee, Connie, Larson, Richard S., ...

A genomic clone coding for the alpha subunit of the mouse complement receptor type 3 and the cellular adhesion molecule Mac-1 has been isolated directly from a genomic library using synthetic...

Selectin receptor–ligand bonds: Formation limited by shear rate and dissociation governed by the Bell model

Chen, Shuqi, Springer, Timothy A.

We have studied the principles that govern the formation and dissociation of an adhesive bond between a cell moving in shear flow and a substrate and tested different theories of how force affects...

Lymphocyte function-associated antigen-1 binding residues in intercellular adhesion molecule-2 (ICAM-2) and the integrin binding surface in the ICAM subfamily

Casasnovas, José M., Pieroni, Cristiana, Springer, Timothy A.

The crystal structure of intercellular adhesion molecule-2 (ICAM-2) revealed significant differences in the presentation of the critical acidic residue important for integrin binding between I and...

The HIV coreceptors CXCR4 and CCR5 are differentially expressed and regulated on human T lymphocytes

Bleul, Conrad C., Wu, Lijun, Hoxie, James A., Springer, Timothy A., Mackay, Charles R.

The chemokine receptors CXCR4 and CCR5 function as coreceptors for HIV-1 entry into CD4+ cells. During the early stages of HIV infection, viral isolates tend to use CCR5 for viral entry, while later...

Experimental support for a β-propeller domain in integrin α-subunits and a calcium binding site on its lower surface

Oxvig, Claus, Springer, Timothy A.

Integrins are large, heterodimeric surface molecules of wide importance in cell adhesion. The N-terminal half of all integrin α-subunits contains seven weak sequence repeats of ≈60 amino acids...

Folding of the conserved domain but not of flanking regions in the integrin β2 subunit requires association with the α subunit

Huang, Chichi, Lu, Chafen, Springer, Timothy A.

We have used immunoprecipitation with mAbs to probe folding during biosynthesis of the β2 integrin subunit of lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18) before and after...

Folding of the β-propeller domain of the integrin αL subunit is independent of the I domain and dependent on the β2 subunit

Huang, Chichi, Springer, Timothy A.

We have studied the folding during biosynthesis of the lymphocyte function-associated antigen 1 (LFA-1) αL subunit using mAb to epitopes that map to seven different regions within the amino acid...

Rolling and transient tethering of leukocytes on antibodies reveal specializations of selectins

Chen, Shuqi, Alon, Ronen, Fuhlbrigge, Robert C., Springer, Timothy A.

Antibodies immobilized on the wall of a flow chamber can support leukocyte rolling in shear flow. IgM mAb to Lewisx (CD15) and sialyl Lewisx (CD15s), which are carbohydrate antigens related to...

Impaired B-lymphopoiesis, myelopoiesis, and derailed cerebellar neuron migration in CXCR4- and SDF-1-deficient mice

Ma, Qing, Jones, Dan, Borghesani, Paul R., Segal, Rosalind A., Nagasawa, Takashi, Kishimoto, Tadamitsu, ...

The chemokine stromal cell-derived factor 1, SDF-1, is an important regulator of leukocyte and hematopoietic precursor migration and pre-B cell proliferation. The receptor for SDF-1, CXCR4, also...

The kinetics and shear threshold of transient and rolling interactions of L-selectin with its ligand on leukocytes

Alon, Ronen, Chen, Shuqi, Fuhlbrigge, Robert, Puri, Kamal D., Springer, Timothy A.

The kinetics of rolling and transient adhesions through selectins may depend on the kinetics and mechanical properties of the selectin:ligand bond, as well as on cellular properties including...

A dimeric crystal structure for the N-terminal two domains of intercellular adhesion molecule-1

Casasnovas, José M., Stehle, Thilo, Liu, Jin-huan, Wang, Jia-huai, Springer, Timothy A.

The 3.0-Å structure of a 190-residue fragment of intercellular adhesion molecule-1 (ICAM-1, CD54) reveals two tandem Ig-superfamily (IgSF) domains. Each of two independent molecules dimerizes...

Defining Extracellular Integrin α-Chain Sites That Affect Cell Adhesion and Adhesion Strengthening without Altering Soluble Ligand Binding

Pujades, Cristina, Alon, Ronen, Yauch, Robert L., Masumoto, Akihide, Burkly, Linda C., Chen, Chun, ...

It was previously shown that mutations of integrin α4 chain sites, within putative EF-hand-type divalent cation-binding domains, each caused a marked reduction in α4β1-dependent cell adhesion....

Conformational changes in tertiary structure near the ligand binding site of an integrin I domain

Oxvig, Claus, Lu, Chafen, Springer, Timothy A.

For efficient ligand binding, integrins must be activated. Specifically, a conformational change has been proposed in a ligand binding domain present within some integrins, the inserted (I) domain...

An isolated, surface-expressed I domain of the integrin αLβ2 is sufficient for strong adhesive function when locked in the open conformation with a disulfide bond

Lu, Chafen, Shimaoka, Motomu, Ferzly, Mazen, Oxvig, Claus, Takagi, Junichi, Springer, Timothy A.

We introduced disulfide bonds to lock the integrin αLβ2 I domain in predicted open, ligand binding or closed, nonbinding conformations. Transfectants expressing αLβ2 heterodimers containing...

Locking in alternate conformations of the integrin αLβ2 I domain with disulfide bonds reveals functional relationships among integrin domains

Lu, Chafen, Shimaoka, Motomu, Zang, Qun, Takagi, Junichi, Springer, Timothy A.

We used integrin αLβ2 heterodimers containing I domains locked open (active) or closed (inactive) with disulfide bonds to investigate regulatory interactions among domains in integrins. mAbs to the...

Reversibly locking a protein fold in an active conformation with a disulfide bond: Integrin αL I domains with high affinity and antagonist activity in vivo

Shimaoka, Motomu, Lu, Chafen, Palframan, Roger T., Von Andrian, Ulrich H., McCormack, Alison, Takagi, Junichi, ...

The integrin αLβ2 has three different domains in its headpiece that have been suggested to either bind ligand or to regulate ligand binding. One of these, the inserted or I domain, has a fold...

Dimerization and the effectiveness of ICAM-1 in mediating LFA-1-dependent adhesion

Jun, Chang-Duk, Shimaoka, Motomu, Carman, Christopher V., Takagi, Junichi, Springer, Timothy A.

Dimeric intercellular adhesion molecule-1 (ICAM-1) binds more efficiently to lymphocyte function-associated antigen-1 (LFA-1) than monomeric ICAM-1. However, it is unknown whether dimerization...

Definition of EGF-like, closely interacting modules that bear activation epitopes in integrin β subunits

Takagi, Junichi, Beglova, Natalia, Yalamanchili, Padmaja, Blacklow, Stephen C., Springer, Timothy A.

Integrin β subunits contain four cysteine-rich repeats in a long extracellular stalk that connects the headpiece to the membrane. Most mAbs to integrin activation epitopes map to these repeats, and...

The Domain Structure of ICAM-1 and the Kinetics of Binding to Rhinovirus

Casasnovas, José M., Bickford, Joanna K., Springer, Timothy A.

Fragments of intercellular adhesion molecule 1 (ICAM- 1) containing only the two most N terminal of its five immunoglobulin SF domains bind to rhinovirus 3 with the same affinity and kinetics as a...

LFA-1 Expression on Target Cells Promotes Human Immunodeficiency Virus Type 1 Infection and Transmission

Hioe, Catarina E., Chien, Peter C., Lu, ChaFen, Springer, Timothy A., Wang, Xiao-Hong, Bandres, Juan, ...

While CD4 and the chemokine receptors are the principal receptors for human immunodeficiency virus (HIV), other cellular proteins, such as LFA-1, are also involved in HIV infection. LFA-1 and its...

Stabilizing the integrin αM inserted domain in alternative conformations with a range of engineered disulfide bonds

Shimaoka, Motomu, Lu, Chafen, Salas, Azucena, Xiao, Tsan, Takagi, Junichi, Springer, Timothy A.

Conformational movement of the C-terminal α7 helix in the integrin inserted (I) domain, a major ligand-binding domain that adopts an α/β Rossmann fold, has been proposed to allosterically regulate...

Structure and allosteric regulation of the αXβ2 integrin I domain

Vorup-Jensen, Thomas, Ostermeier, Christian, Shimaoka, Motomu, Hommel, Ulrich, Springer, Timothy A.

The integrin αXβ2 (CD11c/CD18, p150,95) binds ligands through the I domain of the αX subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense,...

Stabilizing the open conformation of the integrin headpiece with a glycan wedge increases affinity for ligand

Luo, Bing-Hao, Springer, Timothy A., Takagi, Junichi

The affinity of the extracellular domain of integrins for ligand is regulated by conformational changes signaled from the cytoplasm. Alternative types of conformational movement in the ligand-binding...

The Genome of M. acetivorans Reveals Extensive Metabolic and Physiological Diversity

Galagan, James E., Nusbaum, Chad, Roy, Alice, Endrizzi, Matthew G., Macdonald, Pendexter, FitzHugh, Will, ...

Methanogenesis, the biological production of methane, plays a pivotal role in the global carbon cycle and contributes significantly to global warming. The majority of methane in nature is derived...

The Critical Cytoplasmic Regions of the αL/β2 Integrin in Rap1-induced Adhesion and MigrationV⃞

Tohyama, Yumi, Katagiri, Koko, Pardi, Ruggero, Lu, Chafen, Springer, Timothy A., Kinashi, Tatsuo

Rap1 is a potent inside-out signal that increases LFA-1 adhesive activity. In this study, we have defined the cytoplasmic region of the αL and β2 integrin that are required for Rap1-stimulated...

Structure of integrin α5β1 in complex with fibronectin

Takagi, Junichi, Strokovich, Konstantin, Springer, Timothy A., Walz, Thomas

The membrane-distal headpiece of integrins has evolved to specifically bind large extracellular protein ligands, but the molecular architecture of the resulting complexes has not been determined. We...

Activation of integrin β-subunit I-like domains by one-turn C-terminal α-helix deletions

Yang, Wei, Shimaoka, Motomu, Chen, JianFeng, Springer, Timothy A.

Integrins contain two structurally homologous but distantly related domains: an I-like domain that is present in all β-subunits and an I domain that is present in some α-subunits. Atomic resolution...

Intersubunit signal transmission in integrins by a receptor-like interaction with a pull spring

Yang, Wei, Shimaoka, Motomu, Salas, Azucena, Takagi, Junichi, Springer, Timothy A.

The function of some multidomain proteins is regulated by interdomain communication. We use second-site suppressor cysteine mutations to test a hypothesis on how the inserted (I)-like domain in the...

Boca-dependent maturation of β-propeller/EGF modules in low-density lipoprotein receptor proteins

Culi, Joaquim, Springer, Timothy A, Mann, Richard S

The extracellular portions of cell surface receptor proteins are often comprised of independently folding protein domains. As they are translated into the endoplasmic reticulum (ER), some of these...

Partial Purification of Detergent-Soluble HL-A Antigen and Its Cleavage by Papain

Springer, Timothy A., Strominger, Jack L., Mann, Dean

HL-A antigen solubilized with the non-ionic detergent, Brij 99, has been purified to about 50% of homogeneity from a cultured human lymphoblast line. It consists of two nonidentical subunits of...

A Specific Interface between Integrin Transmembrane Helices and Affinity for Ligand

Luo, Bing-Hao, Springer, Timothy A, Takagi, Junichi

Conformational communication across the plasma membrane between the extracellular and intracellular domains of integrins is beginning to be defined by structural work on both domains. However, the...

Integrin β3 regions controlling binding of murine mAb 7E3: Implications for the mechanism of integrin αIIbβ3 activation

Artoni, Andrea, Li, JiHong, Mitchell, Beau, Ruan, Jian, Takagi, Junichi, Springer, Timothy A., ...

Abciximab, a derivative of the murine mAb 7E3, protects against ischemic complications of percutaneous coronary interventions by inhibiting ligand binding to the αIIbβ3 receptor. In this study we...

The integrin α-subunit leg extends at a Ca2+-dependent epitope in the thigh/genu interface upon activation

Xie, Can, Shimaoka, Motomu, Xiao, Tsan, Schwab, Pascale, Klickstein, Lloyd B., Springer, Timothy A.

Two activation-dependent Abs to the integrin αL-subunit were used to study conformational rearrangement of αLβ2 on the cell surface. Activation lowered the concentration of Ca2+ required for...

Exposure of acidic residues as a danger signal for recognition of fibrinogen and other macromolecules by integrin αXβ2

Vorup-Jensen, Thomas, Carman, Christopher V., Shimaoka, Motomu, Schuck, Peter, Svitel, Juraj, Springer, Timothy A.

The structural integrity of tissue proteins is damaged in processes ranging from remodeling of the extracellular matrix to destruction by microbial pathogens. Leukocytes play a prominent role in...

An atomic resolution view of ICAM recognition in a complex between the binding domains of ICAM-3 and integrin αLβ2

Song, Gang, Yang, Yuting, Liu, Jin-huan, Casasnovas, Jose M., Shimaoka, Motomu, Springer, Timothy A., ...

Within the Ig superfamily (IgSF), intercellular adhesion molecules (ICAMs) form a subfamily that binds the leukocyte integrin αLβ2. We report a 1.65-Å-resolution crystal structure of the ICAM-3...

Disrupting integrin transmembrane domain heterodimerization increases ligand binding affinity, not valency or clustering

Luo, Bing-Hao, Carman, Christopher V., Takagi, Junichi, Springer, Timothy A.

Residues important in the interaction between the 23-residue transmembrane (TM) domains of the integrin αIIb- and β3-subunits were identified by mutating each non-Leu residue to Leu. Leu...

Rational Design of Intercellular Adhesion Molecule-1 (ICAM-1) Variants for Antagonizing Integrin Lymphocyte Function-associated Antigen-1-dependent Adhesion*S

Song, Gang, Lazar, Greg A., Kortemme, Tanja, Shimaoka, Motomu, Desjarlais, John R., Baker, David, ...

The interaction between integrin lymphocyte function-associated antigen-1 (LFA-1) and its ligand intercellular adhesion molecule-1 (ICAM-1) is critical in immunological and inflammatory reactions...

Directed evolution to probe protein allostery and integrin I domains of 200,000-fold higher affinity

Jin, Moonsoo, Song, Gang, Carman, Christopher V., Kim, Yong-Sung, Astrof, Nathan S., Shimaoka, Motomu, ...

Understanding allostery may serve to both elucidate mechanisms of protein regulation and provide a basis for engineering active mutants. Herein we describe directed evolution applied to the integrin...

Selectin receptor–ligand bonds: Formation limited by shear rate and dissociation governed by the Bell model

Chen, Shuqi, Springer, Timothy A.

We have studied the principles that govern the formation and dissociation of an adhesive bond between a cell moving in shear flow and a substrate and tested different theories of how force affects...

Lymphocyte function-associated antigen-1 binding residues in intercellular adhesion molecule-2 (ICAM-2) and the integrin binding surface in the ICAM subfamily

Casasnovas, José M., Pieroni, Cristiana, Springer, Timothy A.

The crystal structure of intercellular adhesion molecule-2 (ICAM-2) revealed significant differences in the presentation of the critical acidic residue important for integrin binding between I and...

The HIV coreceptors CXCR4 and CCR5 are differentially expressed and regulated on human T lymphocytes

Bleul, Conrad C., Wu, Lijun, Hoxie, James A., Springer, Timothy A., Mackay, Charles R.

The chemokine receptors CXCR4 and CCR5 function as coreceptors for HIV-1 entry into CD4+ cells. During the early stages of HIV infection, viral isolates tend to use CCR5 for viral entry, while later...

Experimental support for a β-propeller domain in integrin α-subunits and a calcium binding site on its lower surface

Oxvig, Claus, Springer, Timothy A.

Integrins are large, heterodimeric surface molecules of wide importance in cell adhesion. The N-terminal half of all integrin α-subunits contains seven weak sequence repeats of ≈60 amino acids...

Folding of the conserved domain but not of flanking regions in the integrin β2 subunit requires association with the α subunit

Huang, Chichi, Lu, Chafen, Springer, Timothy A.

We have used immunoprecipitation with mAbs to probe folding during biosynthesis of the β2 integrin subunit of lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18) before and after...

Folding of the β-propeller domain of the integrin αL subunit is independent of the I domain and dependent on the β2 subunit

Huang, Chichi, Springer, Timothy A.

We have studied the folding during biosynthesis of the lymphocyte function-associated antigen 1 (LFA-1) αL subunit using mAb to epitopes that map to seven different regions within the amino acid...

Rolling and transient tethering of leukocytes on antibodies reveal specializations of selectins

Chen, Shuqi, Alon, Ronen, Fuhlbrigge, Robert C., Springer, Timothy A.

Antibodies immobilized on the wall of a flow chamber can support leukocyte rolling in shear flow. IgM mAb to Lewisx (CD15) and sialyl Lewisx (CD15s), which are carbohydrate antigens related to...

Impaired B-lymphopoiesis, myelopoiesis, and derailed cerebellar neuron migration in CXCR4- and SDF-1-deficient mice

Ma, Qing, Jones, Dan, Borghesani, Paul R., Segal, Rosalind A., Nagasawa, Takashi, Kishimoto, Tadamitsu, ...

The chemokine stromal cell-derived factor 1, SDF-1, is an important regulator of leukocyte and hematopoietic precursor migration and pre-B cell proliferation. The receptor for SDF-1, CXCR4, also...

The kinetics and shear threshold of transient and rolling interactions of L-selectin with its ligand on leukocytes

Alon, Ronen, Chen, Shuqi, Fuhlbrigge, Robert, Puri, Kamal D., Springer, Timothy A.

The kinetics of rolling and transient adhesions through selectins may depend on the kinetics and mechanical properties of the selectin:ligand bond, as well as on cellular properties including...

A dimeric crystal structure for the N-terminal two domains of intercellular adhesion molecule-1

Casasnovas, José M., Stehle, Thilo, Liu, Jin-huan, Wang, Jia-huai, Springer, Timothy A.

The 3.0-Å structure of a 190-residue fragment of intercellular adhesion molecule-1 (ICAM-1, CD54) reveals two tandem Ig-superfamily (IgSF) domains. Each of two independent molecules dimerizes...

Defining Extracellular Integrin α-Chain Sites That Affect Cell Adhesion and Adhesion Strengthening without Altering Soluble Ligand Binding

Pujades, Cristina, Alon, Ronen, Yauch, Robert L., Masumoto, Akihide, Burkly, Linda C., Chen, Chun, ...

It was previously shown that mutations of integrin α4 chain sites, within putative EF-hand-type divalent cation-binding domains, each caused a marked reduction in α4β1-dependent cell adhesion....

Conformational changes in tertiary structure near the ligand binding site of an integrin I domain

Oxvig, Claus, Lu, Chafen, Springer, Timothy A.

For efficient ligand binding, integrins must be activated. Specifically, a conformational change has been proposed in a ligand binding domain present within some integrins, the inserted (I) domain...

An isolated, surface-expressed I domain of the integrin αLβ2 is sufficient for strong adhesive function when locked in the open conformation with a disulfide bond

Lu, Chafen, Shimaoka, Motomu, Ferzly, Mazen, Oxvig, Claus, Takagi, Junichi, Springer, Timothy A.

We introduced disulfide bonds to lock the integrin αLβ2 I domain in predicted open, ligand binding or closed, nonbinding conformations. Transfectants expressing αLβ2 heterodimers containing...

Locking in alternate conformations of the integrin αLβ2 I domain with disulfide bonds reveals functional relationships among integrin domains

Lu, Chafen, Shimaoka, Motomu, Zang, Qun, Takagi, Junichi, Springer, Timothy A.

We used integrin αLβ2 heterodimers containing I domains locked open (active) or closed (inactive) with disulfide bonds to investigate regulatory interactions among domains in integrins. mAbs to the...

Reversibly locking a protein fold in an active conformation with a disulfide bond: Integrin αL I domains with high affinity and antagonist activity in vivo

Shimaoka, Motomu, Lu, Chafen, Palframan, Roger T., Von Andrian, Ulrich H., McCormack, Alison, Takagi, Junichi, ...

The integrin αLβ2 has three different domains in its headpiece that have been suggested to either bind ligand or to regulate ligand binding. One of these, the inserted or I domain, has a fold...

Dimerization and the effectiveness of ICAM-1 in mediating LFA-1-dependent adhesion

Jun, Chang-Duk, Shimaoka, Motomu, Carman, Christopher V., Takagi, Junichi, Springer, Timothy A.

Dimeric intercellular adhesion molecule-1 (ICAM-1) binds more efficiently to lymphocyte function-associated antigen-1 (LFA-1) than monomeric ICAM-1. However, it is unknown whether dimerization...

Definition of EGF-like, closely interacting modules that bear activation epitopes in integrin β subunits

Takagi, Junichi, Beglova, Natalia, Yalamanchili, Padmaja, Blacklow, Stephen C., Springer, Timothy A.

Integrin β subunits contain four cysteine-rich repeats in a long extracellular stalk that connects the headpiece to the membrane. Most mAbs to integrin activation epitopes map to these repeats, and...

The Domain Structure of ICAM-1 and the Kinetics of Binding to Rhinovirus

Casasnovas, José M., Bickford, Joanna K., Springer, Timothy A.

Fragments of intercellular adhesion molecule 1 (ICAM- 1) containing only the two most N terminal of its five immunoglobulin SF domains bind to rhinovirus 3 with the same affinity and kinetics as a...

LFA-1 Expression on Target Cells Promotes Human Immunodeficiency Virus Type 1 Infection and Transmission

Hioe, Catarina E., Chien, Peter C., Lu, ChaFen, Springer, Timothy A., Wang, Xiao-Hong, Bandres, Juan, ...

While CD4 and the chemokine receptors are the principal receptors for human immunodeficiency virus (HIV), other cellular proteins, such as LFA-1, are also involved in HIV infection. LFA-1 and its...

Stabilizing the integrin αM inserted domain in alternative conformations with a range of engineered disulfide bonds

Shimaoka, Motomu, Lu, Chafen, Salas, Azucena, Xiao, Tsan, Takagi, Junichi, Springer, Timothy A.

Conformational movement of the C-terminal α7 helix in the integrin inserted (I) domain, a major ligand-binding domain that adopts an α/β Rossmann fold, has been proposed to allosterically regulate...

Structure and allosteric regulation of the αXβ2 integrin I domain

Vorup-Jensen, Thomas, Ostermeier, Christian, Shimaoka, Motomu, Hommel, Ulrich, Springer, Timothy A.

The integrin αXβ2 (CD11c/CD18, p150,95) binds ligands through the I domain of the αX subunit. Ligands include the complement factor fragment iC3b, a key component in the innate immune defense,...

Stabilizing the open conformation of the integrin headpiece with a glycan wedge increases affinity for ligand

Luo, Bing-Hao, Springer, Timothy A., Takagi, Junichi

The affinity of the extracellular domain of integrins for ligand is regulated by conformational changes signaled from the cytoplasm. Alternative types of conformational movement in the ligand-binding...

The Genome of M. acetivorans Reveals Extensive Metabolic and Physiological Diversity

Galagan, James E., Nusbaum, Chad, Roy, Alice, Endrizzi, Matthew G., Macdonald, Pendexter, FitzHugh, Will, ...

Methanogenesis, the biological production of methane, plays a pivotal role in the global carbon cycle and contributes significantly to global warming. The majority of methane in nature is derived...

The Critical Cytoplasmic Regions of the αL/β2 Integrin in Rap1-induced Adhesion and MigrationV⃞

Tohyama, Yumi, Katagiri, Koko, Pardi, Ruggero, Lu, Chafen, Springer, Timothy A., Kinashi, Tatsuo

Rap1 is a potent inside-out signal that increases LFA-1 adhesive activity. In this study, we have defined the cytoplasmic region of the αL and β2 integrin that are required for Rap1-stimulated...

Structure of integrin α5β1 in complex with fibronectin

Takagi, Junichi, Strokovich, Konstantin, Springer, Timothy A., Walz, Thomas

The membrane-distal headpiece of integrins has evolved to specifically bind large extracellular protein ligands, but the molecular architecture of the resulting complexes has not been determined. We...

Activation of integrin β-subunit I-like domains by one-turn C-terminal α-helix deletions

Yang, Wei, Shimaoka, Motomu, Chen, JianFeng, Springer, Timothy A.

Integrins contain two structurally homologous but distantly related domains: an I-like domain that is present in all β-subunits and an I domain that is present in some α-subunits. Atomic resolution...

Intersubunit signal transmission in integrins by a receptor-like interaction with a pull spring

Yang, Wei, Shimaoka, Motomu, Salas, Azucena, Takagi, Junichi, Springer, Timothy A.

The function of some multidomain proteins is regulated by interdomain communication. We use second-site suppressor cysteine mutations to test a hypothesis on how the inserted (I)-like domain in the...

Boca-dependent maturation of β-propeller/EGF modules in low-density lipoprotein receptor proteins

Culi, Joaquim, Springer, Timothy A, Mann, Richard S

The extracellular portions of cell surface receptor proteins are often comprised of independently folding protein domains. As they are translated into the endoplasmic reticulum (ER), some of these...

Partial Purification of Detergent-Soluble HL-A Antigen and Its Cleavage by Papain

Springer, Timothy A., Strominger, Jack L., Mann, Dean

HL-A antigen solubilized with the non-ionic detergent, Brij 99, has been purified to about 50% of homogeneity from a cultured human lymphoblast line. It consists of two nonidentical subunits of...

A Specific Interface between Integrin Transmembrane Helices and Affinity for Ligand

Luo, Bing-Hao, Springer, Timothy A, Takagi, Junichi

Conformational communication across the plasma membrane between the extracellular and intracellular domains of integrins is beginning to be defined by structural work on both domains. However, the...

Integrin β3 regions controlling binding of murine mAb 7E3: Implications for the mechanism of integrin αIIbβ3 activation

Artoni, Andrea, Li, JiHong, Mitchell, Beau, Ruan, Jian, Takagi, Junichi, Springer, Timothy A., ...

Abciximab, a derivative of the murine mAb 7E3, protects against ischemic complications of percutaneous coronary interventions by inhibiting ligand binding to the αIIbβ3 receptor. In this study we...

The integrin α-subunit leg extends at a Ca2+-dependent epitope in the thigh/genu interface upon activation

Xie, Can, Shimaoka, Motomu, Xiao, Tsan, Schwab, Pascale, Klickstein, Lloyd B., Springer, Timothy A.

Two activation-dependent Abs to the integrin αL-subunit were used to study conformational rearrangement of αLβ2 on the cell surface. Activation lowered the concentration of Ca2+ required for...

Exposure of acidic residues as a danger signal for recognition of fibrinogen and other macromolecules by integrin αXβ2

Vorup-Jensen, Thomas, Carman, Christopher V., Shimaoka, Motomu, Schuck, Peter, Svitel, Juraj, Springer, Timothy A.

The structural integrity of tissue proteins is damaged in processes ranging from remodeling of the extracellular matrix to destruction by microbial pathogens. Leukocytes play a prominent role in...

An atomic resolution view of ICAM recognition in a complex between the binding domains of ICAM-3 and integrin αLβ2

Song, Gang, Yang, Yuting, Liu, Jin-huan, Casasnovas, Jose M., Shimaoka, Motomu, Springer, Timothy A., ...

Within the Ig superfamily (IgSF), intercellular adhesion molecules (ICAMs) form a subfamily that binds the leukocyte integrin αLβ2. We report a 1.65-Å-resolution crystal structure of the ICAM-3...

Disrupting integrin transmembrane domain heterodimerization increases ligand binding affinity, not valency or clustering

Luo, Bing-Hao, Carman, Christopher V., Takagi, Junichi, Springer, Timothy A.

Residues important in the interaction between the 23-residue transmembrane (TM) domains of the integrin αIIb- and β3-subunits were identified by mutating each non-Leu residue to Leu. Leu...

Directed evolution to probe protein allostery and integrin I domains of 200,000-fold higher affinity

Jin, Moonsoo, Song, Gang, Carman, Christopher V., Kim, Yong-Sung, Astrof, Nathan S., Shimaoka, Motomu, ...

Understanding allostery may serve to both elucidate mechanisms of protein regulation and provide a basis for engineering active mutants. Herein we describe directed evolution applied to the integrin...

Regulation of outside-in signaling and affinity by the β2 I domain of integrin αLβ2

Chen, JianFeng, Yang, Wei, Kim, Minsoo, Carman, Christopher V., Springer, Timothy A.

The adhesiveness of integrin αLβ2 is modulated by divalent cations. We mutated three metal ion-binding sites in the β2 I domain. The metal ion-dependent adhesion site (MIDAS) and the...

AL-57, a ligand-mimetic antibody to integrin LFA-1, reveals chemokine-induced affinity up-regulation in lymphocytes

Shimaoka, Motomu, Kim, Minsoo, Cohen, Edward H., Yang, Wei, Astrof, Nathan, Peer, Dan, ...

Affinity of integrin lymphocyte function-associated antigen 1 (LFA-1) is enhanced by conformational changes from the low-affinity closed form to the high-affinity (HA) open form of the ligand-binding...

Structural transitions of complement component C3 and its activation products

Nishida, Noritaka, Walz, Thomas, Springer, Timothy A.

Complement sensitizes pathogens for phagocytosis and lysis. We use electron microscopy to examine the structural transitions in the activation of the pivotal protein in the complement pathway, C3. In...

A transmigratory cup in leukocyte diapedesis both through individual vascular endothelial cells and between them

Carman, Christopher V., Springer, Timothy A.

The basic route and mechanisms for leukocyte migration across the endothelium remain poorly defined. We provide definitive evidence for transcellular (i.e., through individual endothelial cells)...

The primacy of affinity over clustering in regulation of adhesiveness of the integrin αLβ2

Kim, Minsoo, Carman, Christopher V., Yang, Wei, Salas, Azucena, Springer, Timothy A.

Dynamic regulation of integrin adhesiveness is required for immune cell–cell interactions and leukocyte migration. Here, we investigate the relationship between cell adhesion and integrin...

Specific and covalent labeling of a membrane protein with organic fluorochromes and quantum dots

Bonasio, Roberto, Carman, Christopher V., Kim, Enoch, Sage, Peter T., Love, Kerry R., Mempel, Thorsten R., ...

The real-time observation of protein dynamics in living cells and organisms is of fundamental importance for understanding biological processes. Most approaches to labeling proteins exploit...

Structural plasticity in Ig superfamily domain 4 of ICAM-1 mediates cell surface dimerization

Chen, Xuehui, Kim, Thomas Doohun, Carman, Christopher V., Mi, Li-Zhi, Song, Gang, Springer, Timothy A.

The Ig superfamily (IgSF) intercellular adhesion molecule-1 (ICAM-1) equilibrates between monomeric and dimeric forms on the cell surface, and dimerization enhances cell adhesion. A crystal structure...

Development, standardization and refinement of procedures for evaluating effects of endocrine active compounds on development and sexual differentiation of Xenopus laevis

Lutz, Ilka, Kloas, Werner, Springer, Timothy A., Holden, Larry R., Wolf, Jeff C., Krueger, Henry O., ...

Xenopus laevis has been introduced as a model to study effects of endocrine-active compounds (EAC) on development and sexual differentiation. However, variable and inconsistent data have raised...

B Lymphocyte Chemotaxis Regulated in Association with Microanatomic Localization, Differentiation State, and B Cell Receptor Engagement

Bleul, Conrad C., Schultze, Joachim L., Springer, Timothy A.

Migration of mature B lymphocytes within secondary lymphoid organs and recirculation between these sites are thought to allow B cells to obtain T cell help, to undergo somatic hypermutation, to...

The Kinetics of L-selectin Tethers and the Mechanics of Selectin-mediated Rolling

Alon, Ronen, Chen, Shuqi, Puri, Kamal D., Finger, Erik B., Springer, Timothy A.

Two mechanisms have been proposed for regulating rolling velocities on selectins. These are (a) the intrinsic kinetics of bond dissociation, and (b) the reactive compliance, i.e., the susceptibility...

Tenascin Supports Lymphocyte Rolling

Clark, Rachael A., Erickson, Harold P., Springer, Timothy A.

Tenascin is a large extracellular matrix molecule expressed at specific sites in the adult, including immune system tissues such as the bone marrow, thymus, spleen, and T cell areas of lymph nodes....

L-Selectin Ligands That Are O-glycoprotease Resistant and Distinct from MECA-79 Antigen are Sufficient for Tethering and Rolling of Lymphocytes on Human High Endothelial Venules

Clark, Rachael A., Fuhlbrigge, Robert C., Springer, Timothy A.

During the process of lymphocyte recirculation, lymphocytes bind via L-selectin to sulfated sialyl-Lewisx (sLex)–containing carbohydrate ligands expressed on the surface of high endothelial venules...

An Automatic Braking System That Stabilizes Leukocyte Rolling by an Increase in Selectin Bond Number with Shear

Chen, Shuqi, Springer, Timothy A.

Wall shear stress in postcapillary venules varies widely within and between tissues and in response to inflammation and exercise. However, the speed at which leukocytes roll in vivo has been shown to...

Nonmuscle myosin heavy chain IIA mediates integrin LFA-1 de-adhesion during T lymphocyte migration

Morin, Nicole A., Oakes, Patrick W., Hyun, Young-Min, Lee, Dooyoung, Chin, Y. Eugene, King, Michael R., ...

Precise spatial and temporal regulation of cell adhesion and de-adhesion is critical for dynamic lymphocyte migration. Although a great deal of information has been learned about integrin lymphocyte...

Requirement of α and β subunit transmembrane helix separation for integrin outside-in signaling

Zhu, Jieqing, Carman, Christopher V., Kim, Minsoo, Shimaoka, Motomu, Springer, Timothy A., Luo, Bing-Hao

Adhesion to extracellular ligands through integrins regulates cell shape, migration, growth, and survival. How integrins transmit signals in the outside-to-in direction remains unknown. Whereas in...

Structural basis for distinctive recognition of fibrinogen γC peptide by the platelet integrin αIIbβ3

Springer, Timothy A., Zhu, Jianghai, Xiao, Tsan

Hemostasis and thrombosis (blood clotting) involve fibrinogen binding to integrin αIIbβ3 on platelets, resulting in platelet aggregation. αvβ3 binds fibrinogen via an Arg-Asp-Gly (RGD) motif in...

Structural basis for selectin mechanochemistry

Springer, Timothy A.

Selectins are adhesion molecules that resist large tensile forces applied by hydrodynamic forces to leukocytes binding to vessel walls. In crystals, the liganded (high-affinity) and unliganded...

Transmission of allostery through the lectin domain in selectin-mediated cell adhesion

Waldron, Travis T., Springer, Timothy A.

The selectins are cell adhesion proteins that must resist applied forces to mediate leukocyte tethering and rolling along the endothelium and have 2 conformational states. Selectin–ligand bond...