HYPOTHESIS ABOUT THE FUNCTION OF MEMBRANE-BURIED PROLINE RESIDUES IN TRANSPORT PROTEINS
HYPOTHESIS ABOUT THE FUNCTION OF MEMBRANE-BURIED PROLINE RESIDUES IN TRANSPORT PROTEINS
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DOI：
10.1073/pnas.83.4.917
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发表时间：
1986-02-01
影响因子：
11.1
通讯作者：
DEBER, CM
中科院分区：
文献类型：
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作者：
BRANDL, CJ;DEBER, CM
在一项调查中的跨双层区域的完整的膜蛋白，膜埋脯氨酸残基被发现在几乎所有的运输蛋白检查，而膜埋区域的非运输蛋白在很大程度上缺乏膜内脯氨酸残基。当从代表性的运输和非运输膜蛋白的完整序列的氨基酸进行了分析的脯氨酸残基之间的水与膜结构域的分布，脯氨酸被证明是选择性地排除从膜结构域的非运输蛋白，在雅阁从能量和结构考虑的期望。相比之下，脯氨酸残基在运输蛋白之间均匀分布的水和膜结构域，符合的概念，功能膜埋脯氨酸残基选择性地包括在运输蛋白。由于涉及脯氨酸的顺式肽键出现在蛋白质中，并已被牵连在蛋白质的动态过程中，顺-反异构化的Xaa-脯氨酸肽键（Xaa =未指明的氨基酸）埋在膜内，并由此产生的蛋白质链的重定向提出提供可逆的构象变化所需的调节（打开/关闭）的运输通道。与此功能平行，Xaa-Pro肽键的羰基的相对负性可能促进它们作为质子/阳离子转运过程中阳性物质的膜内配体位点的参与。
In a survey of the bilayer-spanning regions of integral membrane proteins, membrane-buried proline residues were found in nearly all transport proteins examined, whereas membrane-buried regions of nontransport proteins were largely devoid of intramembranous proline residues. When amino acids from the complete sequences of representative sets of transport and nontransport membrane proteins were analyzed for the distribution of proline residues between aqueous vs. membranous domains, proline was shown to be selectively excluded from membranous domains of the nontransport proteins, in accord with expectation from energetic and structural considerations. In contrast, proline residues in transport proteins were evenly distributed between aqueous and membranous domains, consistent with the notion that functional membrane-buried proline residues are selectively included in transport proteins. As cis peptide bonds involving proline arise in proteins and have been implicated in protein dynamic processes, the cis-trans isomerization of an Xaa-Pro peptide bond (Xaa = unspecified amino acid) buried within the membrane-and the resulting redirection of the protein chain-is proposed to provide the reversible conformational change requisite for the regulation (opening/closing) of a transport channel. Parallel to this function, the relatively negative character of the carbonyl groups of Xaa-Pro peptide bonds may promote their participation as intramembranous liganding sites for positive species in proton/cation transport processes.