RECEPTOR-MEDIATED UPTAKE OF IRON FROM LACTOFERRIN

描述(调查人员摘要)：众所周知， 母乳中铁的生物利用度非常高。调查人员 都假设这种高生物利用度是 受体在小肠中的介导机制，促进 从母乳中的主要铁结合蛋白--LF中吸收铁。 初步数据显示，在小型 人类婴幼儿和仔猪的肠道刷状缘膜。在 提出的项目，调查人员打算分离和表征 人LFR与分子大小、等电点、亚基的关系 构型、氨基酸和碳水化合物组成，并研究 Lf和Lfr之间的分子相互作用。一种多克隆抗体 将开发出LFR，并将从人类体内克隆该基因 Lamda-gt11中的小肠cdna文库。将对该基因进行测序 以及由核苷酸序列推导出的氨基酸序列。在……里面 平行实验，将猪的LFR鉴定为抗体 并对LFR基因进行克隆和测序。然后这只小猪将被 作为研究LFR个体发生、定位的动物模型 在小肠中的含量以及铁状态对浓度的影响 以分离的cDNA为探针，对LFR及其mRNA的表达进行分析。使用小猪 悬液中的肠细胞，Lf和LFR的潜在内化将 被研究。总之，这项提案的结果应该会提供一个 详细了解LFR的分子性质及其与LFR的相互作用 Lf和肠细胞铁摄取的机制。有关的信息 LFR的个体发生、在肠道中的定位及铁的影响 LFR的表达情况将从所选的动物模型中获得。

DESCRIPTION (Investigator's Abstract): It is well-known that the bioavailability of iron from human milk is very high. The investigators have hypothesized that this high bioavailability is the result of a receptor-mediated mechanism in the small intestine that facilitates the absorption of iron from LF, the major iron-binding protein in human milk. Preliminary data demonstrate the presence of a specific LFR in the small intestinal brush border membrane of human infants and piglets. In the proposed project, the investigators intend to isolate and characterize the human LFR with regard to molecular size, isoelectric point, subunit arrangement, amino acid and carbohydrate composition and to study the molecular interaction between LF and the LFR. A polyclonal antibody towards LFR will be developed and the gene will be cloned from a human small intestinal cDNA library in lamda-gt11. The gene will be sequenced and the amino acid sequence deduced from the nucleotide sequence. In parallel experiments, the pig LFR will be characterized, an antibody produced and the LFR gene cloned and sequenced. The piglet will then be used as an animal model to study the ontogeny of the LFR, the localization in the small intestine and the effect of iron status on the concentrations of LFR and its mRNA, using the isolated cDNA as a probe. Using piglet enterocytes in suspension, the potential internalization of Lf and LfR will be studied. In conclusion, the results from this proposal should provide a detailed insight into the molecular nature of the LFR, its interaction with LF and the mechanism of iron uptake into the enterocyte. Information on the ontogeny of the LFR, localization in the gut and the effect of iron status on LFR expression will be obtained from the animal model chosen.