RECEPTOR-MEDIATED UPTAKE OF IRON FROM LACTOFERRIN

描述（研究者摘要）：众所周知， 来自人乳的铁的生物利用度非常高。 调查人员 假设这种高生物利用度是由于 受体介导的机制，在小肠，促进 从LF吸收铁，LF是人乳中的主要铁结合蛋白。 初步数据表明，在小的LFR的存在下， 人类婴儿和小猪的肠刷状缘膜。 在 建议的项目，研究人员打算分离和表征 人LFR在分子大小、等电点、亚基 氨基酸和碳水化合物的组成，并研究 LF和LFR之间的分子相互作用。 多克隆抗体 LFR的基因将从人类中克隆出来， λ-gt 11中小肠cDNA文库。 基因将被测序 和由该核苷酸序列推导出的氨基酸序列。 在 平行实验中，猪LFR将被表征，抗体 并对LFR基因进行克隆和测序。 小猪将在 作为动物模型研究LFR的个体发育，定位 以及铁状态对小肠中铁浓度的影响 以分离的cDNA为探针，对LFR及其mRNA进行了定量分析。 使用小猪 肠细胞悬浮液中，Lf和LfR的潜在内化将 被研究。 总之，这项建议的结果应提供一个 详细了解LFR的分子性质，其与 LF与肠上皮细胞铁摄取机制的关系。 信息 LFR的个体发生、在肠道中的定位和铁的作用 从所选动物模型中获得LFR表达的状态。

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.