Hall M N, Schwartz M
Ann Microbiol (Paris). 1982 Jan;133A(1):123-7.
We have reviewed a unique mutation affecting the hydrophilic segment of the lambda-receptor signal sequence. Considering the implications of this mutation, we have proposed a model depicting early steps of protein secretion. The salient, novel features of this model are as follows. 1) The model explicitly states that the LamB protein must initiate the export process to be synthesized. Commitment to synthesis occur subsequent to an interaction between the hydrophilic segment of the signal sequence and a membrane export site, the initial interaction between the nascent secreted protein and the membrane. Implicit in this concept is obligatory co-translational secretion of lambda receptor. 2) We suggest the existence of a "stop translation" sequence. The role of this sequence is to halt translation in order to allow sufficient time for the hydrophilic portion of the signal sequence to initiate export by interacting with a membrane receptor. 3) We suggest that at least part of the "stop translation" sequence is located down-stream from the signal sequence, after residue 15 of the mature LamB protein. 4) We further speculate, albeit in the absence of direct evidence, that the hydrophobic portion of the signal sequence may also be part of the "stop translation" sequence.
我们已研究了一种影响λ受体信号序列亲水片段的独特突变。考虑到该突变的影响，我们提出了一个描述蛋白质分泌早期步骤的模型。该模型的显著新特点如下：1）该模型明确指出，LamB蛋白必须启动输出过程才能进行合成。在信号序列的亲水片段与膜输出位点相互作用之后，即新生分泌蛋白与膜之间的初始相互作用之后，才会发生合成的决定。这一概念中隐含着λ受体的共翻译分泌是必需的。2）我们认为存在一个“停止翻译”序列。该序列的作用是停止翻译，以便有足够的时间让信号序列的亲水部分通过与膜受体相互作用启动输出。3）我们认为“停止翻译”序列的至少一部分位于信号序列下游，在成熟LamB蛋白的第15位残基之后。4）我们进一步推测，尽管缺乏直接证据，但信号序列的疏水部分也可能是“停止翻译”序列的一部分。
