ROLE OF SUGARS IN PHAGOCYTOSIS OF ROD OUTER SEGMENTS

视网膜生理学的一个关键方面是视网膜色素沉着细胞的吞噬作用。 视杆外节盘上皮在视杆更新过程中脱落。 与此过程相关的分子事件知之甚少。 我们将 研究假设，碳水化合物成分的膜， 这些细胞器参与了细胞的识别现象， 视网膜色素上皮细胞作为其吞噬的一个方面。 首先，我们将研究一个模型系统的碳水化合物识别这些 通过研究细胞进行吸附过程的能力， 在碳水化合物组成上不同的糖蛋白的内吞作用。 这些研究的生物学工具将是色素上皮细胞， 鸡胚，保持在文化中;目标分子将是一个 碳水化合物类型不同的一系列125 I-新糖蛋白 目前，以及碘化，纯化的溶酶体酶与建立 标记它们被其他细胞吸收。 这些研究可能揭示了 在视网膜色素上皮细胞的识别系统中， 涉及特定碳水化合物的糖蛋白的内吞作用。 这些研究的第二阶段将调查色素沉着者的能力， 上皮细胞，在培养中，以吞噬牛杆外节，盘 膜，和视紫红质脂质体，以及对这一过程的影响， 通过化学和酶的方法改变它们的碳水化合物。 特别强调 将被放置在修改的碳水化合物的视紫红质的效果， 这些膜。 生物化学、同位素和电子显微镜技术将用于 跟随这些反应。

A key aspect of retinal physiology is the phagocytosis by the retinal pigmented epithelium of rod outer segment discs shed during the process of rod-renewal. Little is known of the molecular events associated with this process. We shall investigate the hypothesis that carbohydrate components on the membranes of these organelles are involved in recognition phenomena with the cells of the retinal pigmented epithelium as an aspect of their engulfment. Initially, we shall examine a model system of carbohydrate recognition by these cells by investigating their ability to carry out the process of adsorptive endocytosis of glycoproteins which differ in their carbohydrate composition. The biological tool for these studies will be the pigmented epithelium cell of the embryonic chick, maintained in culture; the target molecules will be a series of 125I-neoglycoproteins which differ in the type of carbohydrate present, as well as iodinated, purified lysosomal enzymes with established markers for their uptake by other cells. These studies may reveal the presence in the retinal pigment epithelial cell of recognition systems for the endocytosis of glycoproteins involving specific carbohydrates. The second phase of these studies will investigate the ability of the pigmented epithelium cell, in culture, to engulf bovine rod outer segments, disc membranes, and rhodopsin-liposomes, and the influence on this process of modifying their carbohydrates by chemical and enzymatic means. Special emphasis will be placed on the effect of modifying the carbohydrates of rhodopsin in these membranes. Biochemical, isotopic, and electron-microscopic techniques will be used to follow these reactions.