GLYCOLIPID AND GLYCOPROTEIN METABOLISM IN EYE TISSUE

目前对视紫红质的代谢命运知之甚少。 视杆外段视网膜色素上皮(RPE)的吞噬作用 磁盘膜。我们之前的研究表明，牛RPE中存在 一种酶系统，它能将嘌呤视紫红质分解成单一的 糖肽。这些研究是在视紫红质标记的ITS中进行的 珊瑚水合物基团。我们现在希望将更一般的标签引入到 这种分子通过还原甲基化而遵循其余分子的命运 这种糖蛋白。我们会特别注意这方面的能力。 RPE对营养不良大鼠进行视紫红质分解代谢。这 可提供有关营养不良患者代谢能力的信息 以前没有的眼组织。的碳水化合物链 视紫红质与其他天冬酰胺连接的糖蛋白相比是独一无二的。 它们变短的大小表明视网膜中存在特殊控制 调节其生物合成的机制。我们希望对此进行调查 进程。我们将研究寡糖-脂类的性质 视紫红质糖链的前体，以及试图分离 在加工阶段形成的“视紫红质前”中间体 视紫红质糖基化。我们还将调查是否存在 糖基转移酶的活性与细胞的最终组装有关 视紫红质糖链的生物合成及其方法 视网膜来控制这些群体的性质。作为我们的结果 以前关于视紫红质糖基化的研究，证据是 这表明视杆中存在未糖基化的视紫红质 外段盘膜。我们希望探讨这一可能性。 再远一点。非糖化视紫红质的产生，如由 抗生素衣霉素的使用将在牛身上进行体外试验。 视网膜和幼鼠的视网膜，以及大鼠体内的视网膜。 除了这些研究外，糖基化对稳定性的影响 将会检查视紫红质的含量。多醇途径的许多方面 已经由我们的研究人员描述了视网膜中糖蛋白的生物合成 实验室。我们希望继续调查有关机制的问题。 调节“早期”GlcNAc-脂的生物合成。

Little is known of the metabolic fate of rhodopsin following the phagocytosis by the retinal pigment epithelium (RPE) of rod outer segment disc membranes. Our previous studies have shown the presence in bovine RPE of an enzyme system which cleaves purine rhodopsin to a single glycopeptide. These studies were performed with rhodopsin labeled in its corbohydrate groups. We wish now to introduce a more general label into this molecule by reductive methylation and follow the fate of the rest of this glycoprotein. Speical attention will be paid to the capacity of the RPE of the dystrophic rat to carry out the catabolism of rhodopsin. This may provide information concerning the metabolic capacity of dystrophic ocular tissue not previously available. The carbohydrate chains of rhodopsin are unique as compared to other asparagine-linked glycoproteins. Their abridged size suggests the presence in the retina of special control mechanisms regulating their biosynthesis. We wish to investigate this process. We shall investigate the nature of the oligosaccharide-lipid precursors of the sugar chains of rhodopsin, as well as attempt to isolate "pre-rhodopsin" intermediates formed during the processing phase of rhodopsin glycosylation. We shall also investigate the presence of the activity of glycosyltransferases concerned with the final assembly of the biosynthesis of the saccharide chains of rhodopsin and the means used by the retina to control the nature of these groups. As a result of our previous studies dealing with the glycosylation of rhodopsin, evidence was obtained indicating the presence of unglycosylated rhodopsin in the rod outer segment disc membranes. We wish to explore this possibility further. The production of unglycosylated rhodopsin, as brought about by the use of the antibiotic, tunicamycin, will be examined in vitro in bovine retina and in the retina of the young rat, as well as in vivo in the rat. In addition to these studies, the effect of glycosylation on the stability of rhodopsin will be examined. Many of the aspects of the dolichol pathway of glycoprotein biosynthesis in the retinal have been described by our laboratory. We wish to continue our investigations dealing with mechanisms regulating the biosynthesis of the "early" GlcNAc-lipids.