The 33K/BETA-Gamma Transducin Complex of Mammalian Rod Photopeceptors

这个研究项目研究了一种只存在于视网膜感光器中的蛋白质复合物。该复合物由33,000 （33K）道尔顿的磷蛋白和两种蛋白质（β和γ转导蛋白）组成，这两种蛋白质已被证明参与视觉转导过程。β - γ转导蛋白与33K蛋白的关联以及光触发33K去磷酸化的能力表明，33K/T β - γ复合物可能调节光传导过程，特别是在哺乳动物光感受器中。PI将重点关注33K蛋白的光调制磷酸化/去磷酸化周期。33K蛋白的磷酸化可能会改变33K蛋白与转导蛋白β - γ亚基之间的相互作用，或者它可能会改变33K/T β - γ复合物的功能活性。这些研究在更广泛的意义上具有重要意义，因为转导蛋白属于同源gtp结合蛋白（g蛋白）家族，参与多种组织的信号转导。在每个组织中，细胞外信号（如光、激素或神经递质）的受体与调节细胞功能的g蛋白偶联。目前尚不清楚g蛋白是如何下调的，但可能与33K/ t - β - γ复合物类似的蛋白质似乎与此有关。了解调节视觉过程的机制是本项目的主要目标，每一项进展都有助于深入了解磷酸化蛋白如何与G-蛋白家族相互作用，从而影响G-蛋白介导的许多细胞功能。

This research project investigates a protein complex that is found only in retinal photoreceptors. The complex is composed of a phosphoprotein of 33,000 (33K) daltons and two proteins (beta and gamma transducin) which have been shown to participate in the visual transduction process. Association of beta-gamma transducin with the 33K protein and the ability of light to trigger the dephosphorylation of 33K suggests that the 33K/T beta-gamma complex may act to modulate the phototransduction process, particularly in mammalian photoreceptors. The PI will focus on the light-modulated phosphorylation/dephosphorylation cycle of the 33K protein. Phosphorylation of the 33K protein may modify interactions between the 33K protein and the beta-gamma subunits of transducin or it could alter the functional activities of the 33K/T beta-gamma complex. These studies are significant in a broader sense because transducin belongs to a family of homologous GTP-binding proteins (G-proteins) that are involved in signal transduction in a variety of tissues. In each tissue, a receptor for an extracellular signal, e.g., light, hormone or neurotransmitter, is coupled to a G-protein which regulates cellular function. It is still unclear how G-proteins are down-regulated, but proteins which may be analogous to the 33K/T-beta-gamma complex seem to be involved. Understanding the mechanisms which regulate the visual process is a major goal of this project, and each increment of accomplishment provides insight into how phosphoproteins interact with the family of G- proteins and, thereby, influence the many cellular functions which G-proteins mediate.