van der Does C, den Blaauwen T, de Wit J G, Manting E H, Groot N A, Fekkes P, Driessen A J
Department of Microbiology, University of Groningen, Haren, The Netherlands.
Mol Microbiol. 1996 Nov;22(4):619-29. doi: 10.1046/j.1365-2958.1996.d01-1712.x.
SecA is the dissociable ATPase subunit of the Escherichia coli preprotein translocase, and cycles in a nucleotide-modulated manner between the cytosol and the membrane. Overproduction of the integral subunits of the translocase, the SecY, SecE and SecG polypeptides, results in an increased level of membrane-bound SecA. This fraction of SecA is firmly associated with the membrane as it is resistant to extraction with the chaotropic agent urea, and appears to be anchored by SecYEG rather than by lipids. Topology analysis of this membrane-associated form of SecA indicates that it exposes a carboxy-terminal domain to the periplasmic face of the membrane.
SecA是大肠杆菌前体蛋白转位酶中可解离的ATP酶亚基，以核苷酸调节的方式在细胞质和膜之间循环。转位酶的整合亚基SecY、SecE和SecG多肽的过量表达导致膜结合SecA水平升高。这部分SecA与膜紧密结合，因为它对离液剂尿素的提取具有抗性，并且似乎是由SecYEG而非脂质锚定的。对这种膜结合形式的SecA进行拓扑分析表明，它将一个羧基末端结构域暴露于膜的周质面。
