BACTERIORHODOPSIN IS AN INSIDE-OUT PROTEIN
BACTERIORHODOPSIN IS AN INSIDE-OUT PROTEIN
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DOI：
10.1073/pnas.77.10.5894
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发表时间：
1980-01-01
期刊：
影响因子：
--
通讯作者：
ZACCAI, G
中科院分区：
文献类型：
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作者：
ENGELMAN, DM;ZACCAI, G
当结构的某些部分可以进行重氢时，中子散射特别有用。通过生物合成结合，盐生盐杆菌获得了紫色的膜，其中所有的缬氨酸或所有的苯丙氨酸都以氚的形式存在。差分傅立叶技术允许对目的膜结构的突起中的缬氨酸和苯丙氨酸的分布进行总体评估。这些结果表明，缬氨酸分布在单个细菌视紫红质分子的外围，而苯丙氨酸分布在其中心。氨基酸序列是已知的，并且其中大部分可以分配给细菌视紫红质结构的α-螺旋，这一事实被用来解释结果。将MAP与Valine和Pylylalanine在α-螺旋周长附近的分布进行比较，确定了其他氨基酸的分布，并得出结论：细菌视紫红质分子的带电基团和极性基团倾向于位于分子内部，远离与脂类的接触，而非极性表面则指向外部，与脂类区域接触。因此，与可溶性蛋白质的组织相比，蛋白质是由内而外的。
Neutron scattering is particularly useful when parts of a structure can be deuterated. By biosynthetic incorporation, from Halobacterium halobium, purple membranes were obtained in which all of the valines or all of the phenylalanines are present in deuterated form. Difference Fourier techniques permit a general assessment of the distribution of valine and phenylalanine in projections of the purpose membrane structure. These show that valine is distributed toward the periphery of a single bacteriorhodopsin molecule, whereas phenylalanine is distributed toward its center. The facts that the amino acid sequence is known and that much of it can be assigned to the .alpha.-helices of the bacteriorhodopsin structure are used to interpret the results. Comparison of maps with the distribution of valine and phenylalanine around .alpha.-helical perimeters establishes the distribution of other amino acids and leads to the conclusion that the charged and polar groups of the bacteriorhodopsin molecule tend to lie at the molecular interior, away from contact with lipid, while the nonpolar surfaces are directed outward, making contact with the lipid regions. Thus, the protein is inside-out compared with the organization of soluble proteins.