Stader J, Justice S
School of Biological Sciences, University of Missouri-Kansas City 64110-2499.
J Mol Biol. 1994 May 13;238(4):555-62. doi: 10.1006/jmbi.1994.1314.
The production of functional porins involves multiple steps including: export of precursor polypeptides from the cytoplasm, assembly of monomers into trimers, and stabilization of trimers by association with lipopolysaccharide. In this report, a late export/assembly intermediate of the maltoporin (LamB) is found in the inner membrane of Escherichia coli using cell fractionation studies. This processed intermediate is transiently associated with a unique Triton X-100-insoluble subfraction of the inner membrane. The kinetics of appearance and solubility characteristics of this intermediate correspond to those of the metastable trimer form of LamB, suggesting that the export and assembly pathways overlap in the inner membrane prior to final localization in the bulk outer membrane.
功能性孔蛋白的产生涉及多个步骤，包括：前体多肽从细胞质输出、单体组装成三聚体以及三聚体通过与脂多糖结合而稳定。在本报告中，通过细胞分级分离研究在大肠杆菌内膜中发现了麦芽糖孔蛋白（LamB）的晚期输出/组装中间体。这种加工后的中间体与内膜中一种独特的不溶于 Triton X-100 的亚组分短暂相关。该中间体的出现动力学和溶解性特征与 LamB 的亚稳三聚体形式相对应，这表明输出和组装途径在内膜中重叠，然后最终定位于大量的外膜中。
