Domain-Specific Interactions of Talin with the Membrane-Proximal Region of the Integrin β3 Subunit†

Biochemistry ◽  
2003 ◽  
Vol 42 (27) ◽  
pp. 8307-8312 ◽  
Author(s):  
Tobias S. Ulmer ◽  
David A. Calderwood ◽  
Mark H. Ginsberg ◽  
Iain D. Campbell
Keyword(s):  
Proximal Region ◽  
Specific Interactions ◽  
Domain Specific ◽  
Integrin Β3 ◽  
Membrane Proximal Region

scholarly journals Kindlin-2 (Mig-2): a co-activator of β3 integrins

2008 ◽  
Vol 181 (3) ◽  
pp. 439-446 ◽  
Author(s):  
Yan-Qing Ma ◽  
Jun Qin ◽  
Chuanyue Wu ◽  
Edward F. Plow
Keyword(s):  
Proximal Region ◽  
Integrin Activation ◽  
Binding Partner ◽  
Integrin Β3 ◽  
Synergistic Enhancement ◽  
Cytoplasmic Tails ◽  
And Migration ◽  
Sirna Knockdown ◽  
Membrane Proximal Region ◽  
Extracellular Environment

Integrin activation is essential for dynamically linking the extracellular environment and cytoskeletal/signaling networks. Activation is controlled by integrins' short cytoplasmic tails (CTs). It is widely accepted that the head domain of talin (talin-H) can mediate integrin activation by binding to two sites in integrin β's CT; in integrin β3 this is an NPLY747 motif and the membrane-proximal region. Here, we show that the C-terminal region of integrin β3 CT, composed of a conserved TS752T region and NITY759 motif, supports integrin activation by binding to a cytosolic binding partner, kindlin-2, a widely distributed PTB domain protein. Co-transfection of kindlin-2 with talin-H results in a synergistic enhancement of integrin αIIbβ3 activation. Furthermore, siRNA knockdown of endogenous kindlin-2 impairs talin-induced αIIbβ3 activation in transfected CHO cells and blunts αvβ3-mediated adhesion and migration of endothelial cells. Our results thus identify kindlin-2 as a novel regulator of integrin activation; it functions as a coactivator.

Herpes simplex virus glycoprotein B (gB) mutations define structural sites in domain I, the membrane proximal region, and the cytodomain that regulate entry.

2021 ◽  
Author(s):  
Qing Fan ◽  
Richard Longnecker ◽  
Sarah A. Connolly
Keyword(s):  
Cell Fusion ◽  
Virus Entry ◽  
Proximal Region ◽  
Glycoprotein B ◽  
Viral Fusion ◽  
Viral Fusion Protein ◽  
Membrane Proximal Region ◽  
Domain V ◽  
Domain I ◽  
Cell Cell

The viral fusion protein glycoprotein B (gB) is conserved in all herpesviruses and is essential for virus entry. During entry, gB fuses viral and host cell membranes by refolding from a prefusion to a postfusion form. We previously introduced three structure-based mutations (gB-I671A/H681A/F683A) into the domain V arm of the gB ectodomain that resulted in reduced cell-cell fusion. A virus carrying these three mutations (called gB3A) displayed a small plaque phenotype and remarkably delayed entry into cells. To identify mutations that could counteract this phenotype, we serially passaged the gB3A virus and selected for revertant viruses with increased plaque size. Genomic sequencing revealed that the revertant viruses had second-site mutations in gB, including E187A, M742T, and S383F/G645R/V705I/V880G. Using expression constructs encoding these mutations, only gB-V880G was shown to enhance cell-cell fusion. In contrast, all of the revertant viruses showed enhanced entry kinetics, underscoring the fact that cell-cell fusion and virus-cell fusion are different. The results indicate that mutations in three different regions of gB (domain I, the membrane proximal region, and the cytoplasmic tail domain) can counteract the slow entry phenotype of gB3A virus. Mapping these compensatory mutations to prefusion and postfusion structural models suggests sites of intramolecular functional interactions with the gB domain V arm that may contribute to the gB fusion function. Importance The nine human herpesviruses are ubiquitous and cause a range of disease in humans. Glycoprotein B (gB) is an essential viral fusion protein that is conserved in all herpesviruses. During host cell entry, gB mediates virus-cell membrane fusion by undergoing a conformational change. Structural models for the prefusion and postfusion form of gB exist, but the details of how the protein converts from one to the other are unclear. We previously introduced structure-based mutations into gB that inhibited virus entry and fusion. By passaging this entry-deficient virus over time, we selected second-site mutations that partially restore virus entry. The location of these mutations suggest regulatory sites that contribute to fusion and gB refolding during entry. gB is a target of neutralizing antibodies and defining how gB refolds during entry could provide a basis for the development of fusion inhibitors for future research or clinical use.

scholarly journals Ligand-specific utilization of the extracellular membrane-proximal region of the gp130-related signalling receptors

1999 ◽  
Vol 345 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Annet HAMMACHER ◽  
John WIJDENES ◽  
Douglas J. HILTON ◽  
Nicos A. NICOLA ◽  
Richard J. SIMPSON ◽  
...  
Keyword(s):  
Proximal Region ◽  
Leukaemia Inhibitory Factor ◽  
Binding Affinities ◽  
Wild Type ◽  
Correct Orientation ◽  
Fibronectin Type Iii ◽  
Membrane Proximal Region ◽  
Stimulating Factor ◽  
Fibronectin Type

The receptor gp130 is used by the interleukin-6 (IL-6)-type cytokines, which include IL-6 and leukaemia-inhibitory factor (LIF). To investigate the role of the three extracellular membrane-proximal fibronectin-type-III-like (FNIII) modules of gp130 and the related receptor for granulocyte colony-stimulating factor (G-CSFR) in cytokine signal transduction we have transfected into murine myeloid M1-UR21 cells the chimaera (GR-FNIII)gp130, which contains the membrane-proximal FNIII modules of the G-CSFR on a gp130 backbone, and its complement, the chimaera (gp130-FNIII)GR. Whereas the binding affinities of 125I-labelled IL-6 to (GR-FNIII)gp130, or of 125I-Tyr1,3-G-CSF to (gp130-FNIII)GR, were similar to wild-type gp130 and wild-type G-CSFR, respectively, 125I-LIF failed to bind with high affinity to (GR-FNIII)gp130. In assays measuring differentiation the (gp130-FNIII)GR cells were fully responsive to G-CSF, whereas the (GR-FNIII)gp130 cells responded fully to the agonistic anti-gp130 monoclonal antibody (mAb) B-S12, but not to IL-6 or LIF. Neutralizing mAbs that recognize the membrane-proximal FNIII modules of gp130 or the G-CSFR differentially interfered with signalling by B-S12, LIF and G-CSF. The data suggest that B-S12 and G-CSF induce the correct orientation or conformation for signalling by the wild-type and chimaeric homodimeric receptors, that the membrane-proximal region of gp130 is important for the correct formation of the signalling IL-6-IL-6 receptor-gp130 complex and that this region is also involved in LIF-dependent receptor heterodimerization and signalling.

scholarly journals Domain-specific Interactions between the p185neuand Epidermal Growth Factor Receptor Kinases Determine Differential Signaling Outcomes

1999 ◽  
Vol 274 (2) ◽  
pp. 574-583 ◽  
Author(s):  
Xiaolan Qian ◽  
Donald M. O’Rourke ◽  
Zhizhong Fei ◽  
Hong-Tao Zhang ◽  
Chih-Ching Kao ◽  
...  
Keyword(s):  
Epidermal Growth Factor Receptor ◽  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Growth Factor Receptor ◽  
Specific Interactions ◽  
Domain Specific ◽  
Differential Signaling ◽  
Receptor Kinases ◽  
Epidermal Growth

scholarly journals Phosphorylation of the Membrane Proximal Region of Tumor Necrosis Factor Receptor CD120a (p55) at ERK Consensus Sites

2000 ◽  
Vol 275 (10) ◽  
pp. 6996-7003 ◽  
Author(s):  
Annemie A. Van Linden ◽  
Vincent Cottin ◽  
Cheryl Leu ◽  
David W. H. Riches
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Receptor ◽  
Proximal Region ◽  
Membrane Proximal Region ◽  
Necrosis Factor

scholarly journals A membrane-proximal region of the interleukin-2 receptor gamma c chain sufficient for Jak kinase activation and induction of proliferation in T cells.

1996 ◽  
Vol 16 (1) ◽  
pp. 309-317 ◽  
Author(s):  
B H Nelson ◽  
J D Lord ◽  
P D Greenberg
Keyword(s):  
T Cells ◽  
Proliferative Response ◽  
Interleukin 2 ◽  
Receptor Activation ◽  
Proximal Region ◽  
Sh2 Domains ◽  
Receptor Chain ◽  
Mitogenic Signalling ◽  
Macrophage Colony ◽  
Membrane Proximal Region

The interleukin-2 (IL-2) receptor (IL-2R) consists of three distinct subunits (alpha, beta, and gamma c) and regulates proliferation of T lymphocytes. Intracellular signalling results from ligand-mediated heterodimerization of the cytoplasmic domains of the beta and gamma c chains. To identify the residues of gamma c critical to this process, mutations were introduced into the cytoplasmic domain, and the effects on signalling were analyzed in the IL-2-dependent T-cell line CTLL2 and T-helper clone D10, using chimeric IL-2R chains that bind and are activated by granulocyte-macrophage colony-stimulating factor. Whereas previous studies of fibroblasts and transformed T cells have suggested that signalling by gamma c requires both membrane-proximal and C-terminal subdomains, our results for IL-2-dependent T cells demonstrate that the membrane-proximal 52 amino acids are sufficient to mediate a normal proliferative response, including induction of the proto-oncogenes c-myc and c-fos. Although gamma c is phosphorylated on tyrosine upon receptor activation and could potentially interact with downstream molecules containing SH2 domains, cytoplasmic tyrosine residues were dispensable for mitogenic signalling. However, deletion of a membrane-proximal region conserved among other cytokine receptors (cytoplasmic residues 5 to 37) or an adjacent region unique to gamma c (residues 40 to 52) abrogated functional interaction of the receptor chain with the tyrosine kinase Jak3. This correlated with a loss of all signalling events analyzed, including phosphorylation of the IL-2R beta-associated kinase Jak1, expression of c-myc and c-fos, and induction of the proliferative response. Thus, it appears in T cells that Jak3 is a critical mediator of mitogenic signaling by the gamma c chain.

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