Thom J R, Randall L L
Biochemistry/Biophysics Program, Washington State University, Pullman 99164-4660.
J Bacteriol. 1988 Dec;170(12):5654-61. doi: 10.1128/jb.170.12.5654-5661.1988.
During the process of export of maltose-binding protein to the periplasm of Escherichia coli, the leader peptide is involved in at least two steps. The presence of the leader portion of maltose-binding protein was shown to be necessary to mediate initial binding of the precursor to the membrane. However, the presence of a mutationally altered leader which does not sustain export in vivo was sufficient to allow this interaction. Thus, the defect in export which is manifested in vivo by this mutational substitution occurs at a step that follows membrane association, most likely the translocation step. Translocation occurs at discrete sites that are not uniformly distributed over the cytoplasmic membrane. A large proportion of the membrane involved in translocation has a higher density than that of bulk cytoplasmic membrane.
在麦芽糖结合蛋白输出至大肠杆菌周质的过程中，前导肽至少参与两个步骤。已表明麦芽糖结合蛋白前导部分的存在对于介导前体与膜的初始结合是必要的。然而，存在一种在体内不能维持输出的经突变改变的前导肽，却足以允许这种相互作用。因此，这种突变替代在体内表现出的输出缺陷发生在膜结合之后的步骤，很可能是转运步骤。转运发生在细胞质膜上分布不均匀的离散位点。参与转运的大部分膜比细胞质膜整体具有更高的密度。
