THE BINDING CASCADE OF SECB TO SECA TO SECY/E MEDIATES PREPROTEIN TARGETING TO THE ESCHERICHIA-COLI PLASMA-MEMBRANE
THE BINDING CASCADE OF SECB TO SECA TO SECY/E MEDIATES PREPROTEIN TARGETING TO THE ESCHERICHIA-COLI PLASMA-MEMBRANE
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DOI：
10.1016/0092-8674(90)90160-g
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发表时间：
1990-10-19
期刊：
影响因子：
64.5
通讯作者：
WICKNER, W
中科院分区：
文献类型：
--
作者：
HARTL, FU;LECKER, S;WICKNER, W
许多大肠杆菌蛋白的输出，如proOmpA，都需要胞质伴侣SecB和膜结合的前蛋白转位酶。转位酶是一种以SecA蛋白为外周膜结构域，SecY/E蛋白为完整结构域的多亚单位酶。SecB通过与胞浆中的proOmpA结合，防止其在非生产部位聚集或与膜结合。SecA受体与proOmpA-SecB复合体(Kd.apprxeq.6.泰晤士报。10-8M)，通过直接识别两个SecB(Kd.apprxeq.2.泰晤士报。10-7M)，以及前体蛋白的前导区和成熟区。SecB具有稳定前体和将其传递给膜结合的SecA的双重功能，这是该途径的下一步。SecA本身通过其亲和力与膜结合(Kd.apprxeq.4.泰晤士报。10-8M)，用于SecY/E和酸性脂类。作为一个两阶段受体系统，SecB和SecA的功能通过它们之间的亲和力联系在一起。
The export of many Escherichia coli proteins such as proOmpA requires the cytosolic chaperone SecB and the membrane-bound preprotein translocase. Translocase is a multisubunit enzyme with the SecA protein as its peripheral membrane domain and the SecY/E protein as its integral domain. SecB, by binding to proOmpA in the cytosol, prevents its aggregation or association with membranes at nonproductive sites. The SecA receptor binds the proOmpA-SecB complex (Kd .apprxeq. 6 .times. 10-8 M) through direct recognition of both the SecB (Kd .apprxeq. 2 .times. 10-7 M) as well as the leader and mature domains of the precursor protein. SecB has a dual function in stabilizing the precursor and in passing it on to membrane-bound SecA, the next step in the pathway. SecA itself is bound to the membrane by its affinity (Kd .apprxeq. 4 .times. 10-8 M) for SecY/E and for acidic lipids. The functions of SecB and SecA as a two-stage receptor system are linked by their affinity for each other.