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 有和没有CBL结合的IF-CBL受体的定位，c)到 了解IF在CBL，d)TO吸收过程中的代谢去向 了解膜脂对整合和催化的影响 IAP和Na+K+ATPase的功能。获得的回肠抗体 受体及其分离的亚基，不仅用于定义 IF-CBL、Ca++和脂质结合单位，也适用于超微结构 回肠受体的定位。多肽的序列测定 来源于回肠受体或其亚单位，如果将进行 了解它的方向，以及任何可能的序列同源性 存在于受体和IF之间。体内和体外实验将 用[125I]-If-57Ca]CBL进行研究，以了解 如果在肠细胞摄取~(57)Co]CBL的过程中。薄膜装订 [125I]-IF-[57Ca]CBL将用不同亚细胞的提取物进行测试 细胞器以确定这些组分中是否有任何组分释放结合到 如果，IF结构中的任何变化是否对 恰好相反。后一种可能性将通过比较 从犬胃和回肠粘膜中提取的IF的性质。膜 脂肪分析(MVM和BLM)将在发育中的大鼠身上进行 肠道，以研究任何特定或组的血脂的变化是否 对酶的溶解度和活性的变化负责 在开发过程中。疏水锚片将从纯净的 大鼠IAP，结合到脂质体上并将进行测序以了解 IAP的膜取向。膜脂对血管内皮细胞生长的影响 将研究IAP和依赖于Na+K+的ATPase的动力学行为。这些 将从MVM(IAP)和BLM(ATPase)中提纯酶。这些研究 体现在这一建议中将有助于我们理解 刷状边缘的重要蛋白质，它们与吸收有关 和回肠肠细胞的运输功能。

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.