G蛋白与整合素αⅡbβ3的双向信号转导

整合素是一类细胞表面受体家族分子,通过双向信号转导参与细胞与细胞外基质、细胞与细胞的粘附以及细胞的迁移.整合素αⅡbβ3(GPⅡb-Ⅲa)特异表达于巨核/血小板系,并且是其含量最多的膜糖蛋白,介导血小板的粘附、伸展、聚集等.G蛋白在整合素αⅡbβ3双向信号转导中发挥重要作用,其中较受关注的是:异源三聚体G蛋白和小G蛋白Rap1参与整合素αⅡbβ3的内向外信号转导;小G蛋白(Rho A、Rac等)和Gα13参与整合素αⅡbβ3的外向内信号转导.在蛋白质结构与功能关系的层面,本文总结了G蛋白的结构、分类、功能以及近年来G蛋白在整合素αⅡbβ3双向信号转导中作用的研究进展.

G Protein and Integrin αIIbβ3 Bidirectional Signal Transduction

Integrin is a family of cell surface receptors, involving in cell-extracellular matrix, cell-cell adhesion and cell migration. Integrin αⅡbβ3 (GPⅡb-Ⅲa), the most abundant membrane glycoprotein in platelets exclusively expressed in megakaryocyte/platelet lineage, mediates platelet adhesion, spread and aggregation. Heterologous trimer G protein and small G protein Rap1 are implicated in integrin αⅡbβ3 inside-out signaling and the small G proteins (RhoA, Rac, etc.) and Gα13 in outside-in signaling highlighting a critical role of G proteins in integrin αⅡbβ3 bidirectional signaling. This review summarizes the domain structure, classification and molecular activities of G proteins and provides a current overview of the roles of G proteins in integrin αⅡbβ3 bidirectional signal transduction.