STUDIES ON INTESTINAL BRUSH BORDER MEMBRANES

本提案的总体目标是了解a）IF-cbl，Ca++， 和回肠受体的脂质结合结构，B）超微结构 在有和没有cbl键的情况下IF-cbl受体的定位，c） 了解IF在cbl吸收过程中的代谢命运，d） 了解膜脂对整合和催化的影响 IAP和Na+K+ ATP酶的功能。 获得的回肠抗体 受体及其分离的亚基，将不仅用于定义 IF-cbl、Ca++和脂质结合单位，以及超微结构 回肠受体的定位。 肽的序列测定 来源于回肠受体或其亚基的免疫抑制剂和IF将进行， 了解它的方向，以及任何可能的序列同源性， 在受体和IF之间存在。 体内和体外实验将 使用[125 I]-IF-57 Ca]cbl进行，以了解 [57 Co]cbl被肠上皮细胞摄取期间。 膜结合 [125 I]-IF-[57 Ca]cBL将使用各种亚细胞提取物进行测试 细胞器，以确定这些组分中的任何一种是否释放与 IF，以及IF结构的任何改变是否负责 反面. 后一种可能性将通过比较 从犬胃和回肠粘膜获得的IF的性质。 膜 将在发育中的大鼠中进行脂质分析（MVM和BLM 肠，研究是否在任何特定的或组的脂质的变化， 负责酶的溶解度和活性的变化 在发展过程中。 疏水性锚件将从纯 大鼠IAP，结合到脂质体，并将进行测序，以了解 IAP的膜取向。 膜脂对细胞膜的影响 研究了IAP和Na+-K+依赖的ATP酶的动力学行为。 这些 将从MVM（IAP）和BLM（ATP酶）中纯化酶。 研究 这一建议将有助于我们了解 刷状缘的重要蛋白质，其与吸收有关 和回肠肠上皮细胞的运输功能。

The overall objective of this proposal is to understand a) IF-cbl, Ca++, and lipid binding structures of ileal receptor, b) ulstrastructural localization of IF-cbl receptor with and without cbl bond to it, c) to understand metabolic fate of IF during the absorption of cbl, d) to understand the effect of membrane lipids on the integration and catalytic function of IAP and Na+K+ ATPase. The antibodies obtained for ileal receptor and its isolated subunits, will be used not only for defining IF-cbl, Ca++, and lipid binding units, but also for ultrastructural localization of the ileal receptor. Sequence determination of peptides derived from ileal receptor or its subunits and IF will be carried out to understand its orientation, and any possible sequence homology that could exist between the receptor and IF. In vivo and in vitro experiments will be undertaken using [125I]-IF-57Ca]cbl to understand the metabolic fate of IF, during the uptake of [57Co]cbl by the enterocyte. Membrane bound [125I]-IF-[57Ca]cbl will be tested with extracts from various subcellular organelles to determine whether any of these fractions release cbl bound to IF, and whether any alteration in the structure of IF is responsible for the reverse. The latter possibility will be studied by comparing the properties of IF obtained from canine gastric and ileal mucosa. Membrane lipid analysis (MVM and BLM) will be undertaken in a developing rat intestine, to study whether changes in any specific or groups of lipids are responsible for the changes in the solubility and activity of enzymes noted during development. Hydrophobic anchor piece will be obtained from pure rat IAP, bound to liposomes and will be sequenced to understand the membrane orientation of IAP. The influence of membrane lipids on the kinetic behaviors of IAP and Na+K+ dependent ATPase will be studied. These enzymes will be purified from MVM (IAP) and BLM (ATPase). The studies embodied in this proposal will help us to understand the nature of the important proteins of brush borders, which are implicated in the absorption and transport functions of ileal enterocytes.