CYSTEINE-RICH INTESTINAL PROTEIN BINDS ZINC DURING TRANSMUCOSAL ZINC TRANSPORT
CYSTEINE-RICH INTESTINAL PROTEIN BINDS ZINC DURING TRANSMUCOSAL ZINC TRANSPORT
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DOI：
10.1073/pnas.88.21.9671
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发表时间：
1991-11-01
影响因子：
11.1
通讯作者：
COUSINS, RJ
中科院分区：
文献类型：
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作者：
HEMPE, JM;COUSINS, RJ
锌吸收的机制尚未阐明，但动力学研究表明，被动和载体介导的过程都涉及。我们已经确定了一个低分子量的锌结合蛋白在大鼠肠粘膜的可溶性部分，可以作为细胞内锌载体。在肝脏或胰腺中未检测到该蛋白，表明其作用特异于肠道。该蛋白质在锌的跨粘膜转运过程中结合锌，并在较高的管腔锌浓度下显示饱和迹象，其特征与载体介导的锌吸收中的作用一致。通过凝胶过滤HPLC和SDS/PAGE纯化的蛋白质的微序列分析显示，在前41个N-末端氨基酸内与富含半胱氨酸的肠蛋白的推导的蛋白质序列完全相同[Birkenmeier，E. H.和戈登，J. I.等人（1986）Proc. Acad. Sci. USA 83，2516-2520]。这些研究人员表明，这种蛋白质的基因在哺乳期的新生儿中受到发育调控，在许多脊椎动物物种中保守，主要在小肠中表达。富含半胱氨酸的肠蛋白含有最近确定的组氨酸和半胱氨酸残基的保守序列，LIM基序，我们的研究结果表明，赋予金属结合特性，这是重要的锌运输和/或这种微量营养素的功能。
The mechanism of zinc absorption has not been delineated, but kinetic studies show that both passive and carrier-mediated processes are involved. We have identified a low molecular mass zinc-binding protein in the soluble fraction of rat intestinal mucosa that could function as an intracellular zinc carrier. The protein was not detected in liver or pancreas, suggesting a role specific to the intestine. The protein binds zinc during transmucosal zinc transport and shows signs of saturation at higher luminal zinc concentrations, characteristics consistent with a role in carrier-mediated zinc absorption. Microsequence analysis of the protein purified by gel-filtration HPLC and SDS/PAGE showed complete identity within the first 41 N-terminal amino acids with the deduced protein sequence of cysteine-rich intestinal protein [Birkenmeier, E. H. & Gordon, J. I. (1986) Proc. Natl. Acad. Sci. USA 83, 2516-2520]. These investigators showed that the gene for this protein is developmentally regulated in neonates during the suckling period, conserved in many vertebrate species, and predominantly expressed in the small intestine. Cysteine-rich intestinal protein contains a recently identified conserved sequence of histidine and cysteine residues, the LIM motif, which our results suggest confers metal-binding properties that are important for zinc transport and/or functions of this micronutrient.