ISOLATION OF GP330/MEGALIN INTERACTING PROTEINS

我们最近分离了编码一种结合蛋白的部分cdna。 一种膜受体的羧基末端尾巴，称为 Gp330/megalin。Gp330是一种大的糖蛋白受体，它已经被 被证明是与Heymann肾炎有关的抗原，一种大鼠模型 人膜性肾小球肾炎。Gp330的表达只是 在肾等上皮细胞的顶面表达 近端小管刷缘。我们拥有的截短蛋白质 分离的包含最近发现的一个已知的蛋白质相互作用结构域 作为PDZ域。这个结构域已被证明与一种氨基酸结合 细胞表面极端羧基末端发现的序列基序 感受器。Gp330包含这样一个基序，人们认为 被截断的蛋白质，我们称之为GAP，可能是一种生理学的 与gp330结合的伙伴。大多数含有PDZ结构域的蛋白质都具有功能 在将受体和通道蛋白定位到细胞的不同区域中 例如神经元突触和细胞间的接触。我们将进行克隆 全长GAP基因，试图更多地了解这些蛋白质 通过鉴定其他相互作用的蛋白质来发挥作用 域名。此外，我们还将描述喘息的相互作用 在分子水平上与gp330进行比对，试图提供证据 GAP参与gp330的本地化和功能。 肾上皮细胞。

We have recently isolated a partial cDNA encoding a protein which binds to the carboxy-terminal tail of a membrane receptor known as gp330/megalin. gp330 is a large glycoprotein receptor that has been shown to be the antigen involved in Heymann nephritis, a rat model of human membranous glomerulonephritis. The expression of gp330 is only expressed on the apical surface of epithelial cells such as the kidney proximal tubule brush border. The truncated protein which we have isolated contains a recently identified protein interaction domain known as the PDZ domain. This domain has been shown to bind to an amino acid sequence motif found at the extreme carboxy-terminus of cell surface receptors. gp330 contains such a motif and it is believed that the truncated protein, which we have named GASP, may be a physiological binding partner to gp330. Most proteins containing PDZ domains function in localizing receptor and channel proteins to distinct areas of a cell such as neuronal synapses and cell-to-cell contacts. We will be cloning the full length GASP cDNA in an attempt to learn more about the proteins function through the identification of other protein interacting domains. In addition, we will be characterizing the interaction of GASP with gp330 at the molecular level in an attempt to provide evidence that GASP is involved in the localization and function of gp330 within the kidney epithelia.