STRUCTURE DEFINITION OF IGF I RECEPTOR FUNCTIONAL DOMAIN

胰岛素样生长因子I（IGF I）在介导胰岛素抵抗中起关键作用。 垂体生长激素的作用 在反应细胞中，IGF I 在质膜上与IGF I受体相互作用， 由两个二硫键连接的α-β 二聚体。 IGF I结合引起内源性胰岛素受体的跨膜激活。 IGF I受体的催化活性，但其机制 目前还没有很好的理解。 在本申请中，我们建议 研究功能定义域的结构和相互作用， IGF I受体。 为此，提出了六个具体目标。 首先，严格分析IGF I受体与胰岛素抵抗的关系， 自磷酸化激活激酶活性， 将进行IGF I缺失。 第二，IGF I 将分析通过二硫键形成的受体α-β二聚体。 第三，纯化的IGF I中IGF I和IGF II的结合结构域 受体将被定义。 包含IGF I和IGF II结合的肽 IGF I受体的结构域将在亲和交叉- 连接和溴化氰处理纯化的IGF I受体，和 抗-肽抗体，其针对所述细胞的表面暴露部分， IGF I受体将被开发和表征。 第四， 将鉴定体外和体内IGF I受体自磷酸化。 第五，IGF I受体磷酸化的功能后果 通过蛋白激酶C和该修饰发生的位点， 将确定体外和体内。 最后是IGF的内源性底物 将研究细胞中I受体酪氨酸激酶活性。 在 这些研究，氧化苯胂，一种三价砷， 据报道，增强内源性底物磷酸化的检测 在胰岛素和IGF I刺激的细胞中，将使用。 的能力 氧化苯胂抑制IGF I刺激的生物活性， 在IGF I存在的情况下， 和氧化苯胂。 预计这些 研究将导致更好地了解信号转导的 IGF I受体及其在人类生长中的作用

Insulin-like growth factor I (IGF I) plays a key role in mediating the growth effects of pituitary growth hormone. In responsive cells, IGF I interacts at the plasma membrane with the IGF I receptor, a heterotetrameric glycoprotein composed of two disulfide-linked alpha-beta dimers. IGF I binding causes the transmembrane activation of the intrinsic catalytic activity of the IGF I receptor, but the mechanism by which this occurs is not yet well understood. In this application, we propose to study the structure and interaction of the functionally-defined domains of the IGF I receptor. To accomplish this, six specific aims are proposed. First, a rigorous analysis of the relationship of IGF I receptor autophosphorylation to activation of kinase activity in the presence and absence of IGF I will be performed. Second, the association of IGF I receptor alpha-beta dimers by disulfide bond formation will be analyzed. Third, the binding domain(s) for IGF I and IGF II in the purified IGF I receptor will be defined. Peptides comprising the IGF I and IGF II binding domains of the IGF I receptor will be identified following affinity cross- linking and cyanogen bromide treatment of the purified IGF I receptor, and anti-peptide antibodies directed against surface-exposed portions of the IGF I receptor will be developed and characterized. Fourth, the sites of IGF I receptor autophosphorylation in vitro and in vivo will be identified. Fifth, the functional consequences of phosphorylation of the IGF I receptor by protein kinase C and the sites at which this modification occurs in vitro and in vivo will be determined. Finally endogenous substrates of IGF I receptor tyrosine kinase activity in cells will be investigated. In these studies, phenylarsine oxide, a trivalent arsenical which has been reported to enhance the detection of endogenous substrates phosphorylated in insulin- and IGF I-stimulated cells, will be employed. The ability of phenylarsine oxide to inhibit IGF I-stimulated biological activities will be examined, and phosphoproteins that accumulate in the presence of IGF I and phenylarsine oxide will be identified. It is anticipated that these studies will lead to a better understanding of signal transduction by the IGF I receptor and its role in human growth.