Inouye M, Halegoua S
CRC Crit Rev Biochem. 1980;7(4):339-71. doi: 10.3109/10409238009105465.
The envelope of Escherichia coli consists of two distinct membranes, the outer membrane and the cytoplasmic membrane. The space between the two membranes is called the periplasmic space, and each fraction contains its own specific proteins. In this review, it is discussed how proteins are localized in their final locations in the envelope. Proteins localized in the outer membrane and the periplasmic space as well as transmembranous proteins in the cytoplasmic membranes appear to be produced from their precursors which have peptide extensions of about 20 amino acid residues at the amino terminal ends. General features for the peptide extension are deduced from the known sequences of the peptide extensions, and, based on their known properties, a hypothesis (loop model) is proposed to explain the possible functions of the peptide extension during the mechanism of secretion across the cytoplasmic membrane.
大肠杆菌的包膜由两个不同的膜组成，即外膜和细胞质膜。这两个膜之间的空间称为周质空间，每个部分都含有其特定的蛋白质。在这篇综述中，讨论了蛋白质如何定位在包膜中的最终位置。定位在外膜和周质空间的蛋白质以及细胞质膜中的跨膜蛋白似乎是由其前体产生的，这些前体在氨基末端有大约20个氨基酸残基的肽延伸。从肽延伸的已知序列推导出肽延伸的一般特征，并根据其已知特性提出一个假设（环模型）来解释肽延伸在跨细胞质膜分泌机制中的可能功能。
