Mechanistic Insights from a Refined Three-dimensional Model of Integrin alphaIIbbeta3

@article{citeulike:2967311, abstract = {The integrin {alpha}IIb{beta}3 plays an important role in platelet function, and abnormalities of this protein result in a serious bleeding disorder, known as Glanzmann thrombasthenia. Although crystallographic data exist for the related integrin {alpha}V{beta}3, to date, there are no high resolution structures of integrin {alpha}IIb{beta}3 available in the literature. Therefore, it is still unclear how specific elements of the {alpha}IIb subunit contribute to integrin {alpha}IIb{beta}3 function. Here we describe a refined model of the {alpha}IIb N-terminal portion of integrin {alpha}IIb{beta}3 obtained by using the {alpha}V{beta}3 template combined with a new method for predicting the conformations of the unique {alpha}IIb loop regions comprising residues 71-85, 114-125, and 148-164. The refined model was probed based on a structural prediction that differentiates it from standard homology models: specifically, that Lys-118 of {alpha}IIb contacts Glu-171 of {beta}3. To test this hypothesis experimentally, the mutant integrin chains {alpha}IIb K118C and {beta}3 E171C were cotransfected into HEK 293 cells. We show that the cells expressed the mutants {alpha}IIb{beta}3 on their surface as a disulfide-linked dimer, supporting the close proximity between {alpha}IIb Lys-118 and {beta}3 Glu-171 predicted from the refined model. This validated model provides a specific structural context for the analysis and interpretation of structure-function relations of integrin {alpha}IIb{beta}3. In addition, it suggests mechanistic hypotheses pertaining to both naturally occurring mutations responsible for Glanzmann thrombasthenia and to point mutations that affect ligand binding. 10.1074/jbc.M400243200}, author = {Filizola, Marta and Hassan, Sergio A. and Artoni, Andrea and Coller, Barry S. and Weinstein, Harel }, citeulike-article-id = {2967311}, doi = {10.1074/jbc.M400243200}, journal = {J. Biol. Chem.}, keywords = {mechanotransduction}, month = {June}, number = {23}, pages = {24624--24630}, posted-at = {2008-07-06 14:41:45}, priority = {2}, title = {Mechanistic Insights from a Refined Three-dimensional Model of Integrin {alpha}IIb{beta}3}, url = {http://dx.doi.org/10.1074/jbc.M400243200}, volume = {279}, year = {2004} }

TY - JOUR ID - citeulike:2967311 L3 - citeulike-article-id:2967311 TI - Mechanistic Insights from a Refined Three-dimensional Model of Integrin {alpha}IIb{beta}3 JF - J. Biol. Chem. VL - 279 IS - 23 SP - 24624 EP - 24630 N2 - The integrin {alpha}IIb{beta}3 plays an important role in platelet function, and abnormalities of this protein result in a serious bleeding disorder, known as Glanzmann thrombasthenia. Although crystallographic data exist for the related integrin {alpha}V{beta}3, to date, there are no high resolution structures of integrin {alpha}IIb{beta}3 available in the literature. Therefore, it is still unclear how specific elements of the {alpha}IIb subunit contribute to integrin {alpha}IIb{beta}3 function. Here we describe a refined model of the {alpha}IIb N-terminal portion of integrin {alpha}IIb{beta}3 obtained by using the {alpha}V{beta}3 template combined with a new method for predicting the conformations of the unique {alpha}IIb loop regions comprising residues 71-85, 114-125, and 148-164. The refined model was probed based on a structural prediction that differentiates it from standard homology models: specifically, that Lys-118 of {alpha}IIb contacts Glu-171 of {beta}3. To test this hypothesis experimentally, the mutant integrin chains {alpha}IIb K118C and {beta}3 E171C were cotransfected into HEK 293 cells. We show that the cells expressed the mutants {alpha}IIb{beta}3 on their surface as a disulfide-linked dimer, supporting the close proximity between {alpha}IIb Lys-118 and {beta}3 Glu-171 predicted from the refined model. This validated model provides a specific structural context for the analysis and interpretation of structure-function relations of integrin {alpha}IIb{beta}3. In addition, it suggests mechanistic hypotheses pertaining to both naturally occurring mutations responsible for Glanzmann thrombasthenia and to point mutations that affect ligand binding. 10.1074/jbc.M400243200 KW - mechanotransduction AU - Filizola, Marta AU - Hassan, Sergio AU - Artoni, Andrea AU - Coller, Barry AU - Weinstein, Harel PY - 2004/06/04/ UR - http://dx.doi.org/10.1074/jbc.M400243200 ER -