King Charles C, Newton Alexandra C
Department of Pharmacology, University of California at San Diego, La Jolla, California 92093-0721, USA.
J Biol Chem. 2004 Sep 3;279(36):37518-27. doi: 10.1074/jbc.M405340200. Epub 2004 Jun 21.
The metabolic actions of insulin are transduced through the phosphatidylinositol 3-kinase pathway. A critical component of this pathway is 3-phosphoinositide-dependent kinase-1 (PDK-1), a PH domain-containing enzyme that catalyzes the activating phosphorylation for many AGC kinases, including Akt and protein kinase C isozymes. We used a directed proteomics-based approach to identify the adaptor protein Grb14, which binds the insulin receptor through an SH2 domain, as a novel PDK-1 binding partner. Interaction of these two proteins is constitutive and mediated by a PDK-1 binding motif on Grb14. Disruption of this motif by point mutation or deletion of the Grb14 SH2 domain prevents the insulin-triggered membrane translocation of PDK-1. The interaction of PDK-1 with Grb14 facilitates Akt function: disruption of the interaction by overexpression of a construct of Grb14 mutated in the PDK-1 binding motif significantly decreases insulin-dependent activation of Akt. Thus, Grb14 serves as an adaptor protein to recruit PDK-1 to activated insulin receptor, thus promoting Akt phosphorylation and transduction of the insulin signal.
胰岛素的代谢作用是通过磷脂酰肌醇3-激酶途径来传导的。该途径的一个关键成分是3-磷酸肌醇依赖性激酶-1（PDK-1），它是一种含有PH结构域的酶，可催化包括Akt和蛋白激酶C同工酶在内的许多AGC激酶的激活磷酸化。我们使用基于定向蛋白质组学的方法，鉴定出衔接蛋白Grb14作为一种新的PDK-1结合伴侣，它通过一个SH2结构域与胰岛素受体结合。这两种蛋白质的相互作用是组成性的，由Grb14上的一个PDK-1结合基序介导。通过点突变或缺失Grb14的SH2结构域破坏该基序，可阻止胰岛素触发的PDK-1膜易位。PDK-1与Grb14的相互作用促进了Akt的功能：在PDK-1结合基序中发生突变的Grb14构建体的过表达破坏这种相互作用，会显著降低胰岛素依赖性的Akt激活。因此，Grb14作为一种衔接蛋白，将PDK-1募集到激活的胰岛素受体上，从而促进Akt磷酸化和胰岛素信号的转导。
