Structure Function Analysis of Integrins alpha1beta1 and alpha2beta2

描述（由申请人提供）：整合素是由非共价结合的α和β亚基形成的跨膜受体。β -1亚基结合12个α亚基，表明α - β -1整合素的功能特异性是由α亚基决定的。这在两种主要的胶原结合受体，整合素α -1- β -1和α -2- β -1中可见，它们不仅对各种胶原具有不同的亲和力（由它们的细胞外结构域决定），而且还以一种严重依赖于它们的跨膜（TM）和细胞质（CT）结构域的方式介导不同的信号。含有整合素的β -1的TM和CT结构域转导信号的分子机制尚不清楚，因为大多数发表的关于这些结构域的研究都是用高度可调节的α -s- β -3整合素进行的，主要集中在β -3亚基本身。我们最近发现，整合素α -1和α -2 TM和CT结构域对整合素α -1- β -1和α -2- β -1功能的特异性有很大的影响。此外，已经确定了通过整合素α -1和α -2 CT尾部调节特定信号传导的关键氨基酸。因此，本项目的总体目标是确定整合素α -1- β -1和α -2- β -1的TM和CT结构域有助于其功能特异性的机制。特别是，我们将验证整合素α -1- β -1和α -2- β -1的TM或CT结构域内的特定残基对于赋予结构和功能特异性至关重要的假设。为了验证这一假设，我们将：目标1)确定单个积分α -1、α -2和β -1 TM/CT结构域以及α -1- β -1和α -2- β -1 TM/CT异源二聚体的结构。目的2)确定控制整合素α -1- β -1和α -2- β -1的α -1和α -2 TM结构域在细胞功能中的特异性和功能的关键氨基酸。目的3)建立TM/CD结构域在整合素α -1- β -1和α -2- β -1功能和特异性中的作用模型。

DESCRIPTION (provided by applicant): Integrins are transmembrane receptors formed by non-covalently bound alpha and beta subunits. The beta-1 subunit binds 12 alpha subunits, suggesting that specificity of function of alpha-beta-1 integrins are determined by the alpha subunits. This is seen in the two major collagen binding receptors, integrins alpha-1-beta-1 and alpha-2-beta-1, which not only have different affinities for various collagens (determined by their extracellular domains), but also mediate different signals in a manner that is critically dependent on their transmembrane (TM) and cytoplasmic (CT) domains. The molecular mechanisms whereby the TM and CT domains of beta-1 containing integrins transduce signals are poorly understood, as most published work on these domains was performed with the highly modulatable alpha-s-beta-3 integrins and focused primarily on the beta-3 subunit itself. We recently showed that integrin alpha-1 and alpha-2 TM and CT domains contribute to the very different specificities of integrin alpha-1-beta-1 and alpha-2-beta-1 function. Moreover, key amino acids that regulate specific signaling by the integrin alpha-1 and alpha-2 CT tails have been identified. Thus, the overall goal of this project is to identify the mechanisms whereby the TM and CT domains of integrins alpha-1-beta-1 and alpha-2-beta-1 contribute to their functional specificity. In particular, we will test the hypothesis that specific residues within the TM or CT domains of integrins alpha-1-beta-1 and alpha-2-beta-1 are critical for conferring structural and functional specificity. To test this hypothesis we will: Aim 1) Determine the structures of the individual integral alpha-1, alpha-2, and beta-1 TM/CT domains and of the alpha-1-beta-1 and alpha-2-beta-1 TM/CT heterodimers. Aim 2) Determine the critical amino acids that govern the specificity and functionality of the alpha-1 and alpha-2 TM domains of integrins alpha-1-beta-1 and alpha-2-beta-1 in cell function. Aim 3) Develop models for the roles of the TM/CD domains in integrin alpha-1-beta-1 and alpha-2-beta-1 function and specificity.