Eble B E, MacRae D R, Lingappa V R, Ganem D
Department of Microbiology and Immunology, University of California Medical Center, San Francisco 94143.
Mol Cell Biol. 1987 Oct;7(10):3591-601. doi: 10.1128/mcb.7.10.3591-3601.1987.
To investigate the mechanism by which complex membrane proteins achieve their correct transmembrane orientation, we examined in detail the hepatitis B surface antigen for sequences which determine its membrane topology. The results demonstrated the presence of at least two kinds of topogenic elements: an N-terminal uncleaved signal sequence and an internal element containing both signal and stop-transfer function. Fusion of reporter groups to either end of the protein suggested that both termini are translocated across the membrane bilayer. We propose that this topology is generated by the conjoint action of both elements and involves a specifically oriented membrane insertion event mediated by the internal sequence. The functional properties of each element can be instructively compared with those of simpler membrane proteins and may provide insight into the generation of other complex protein topologies.
为了研究复杂膜蛋白实现其正确跨膜取向的机制，我们详细研究了乙肝表面抗原中决定其膜拓扑结构的序列。结果表明至少存在两种拓扑形成元件：一个未切割的N端信号序列和一个兼具信号与终止转移功能的内部元件。将报告基团融合到该蛋白的任一端，结果表明两个末端均穿过膜双层进行转运。我们提出，这种拓扑结构是由这两种元件的共同作用产生的，并且涉及由内部序列介导的特定取向的膜插入事件。每个元件的功能特性可以与更简单的膜蛋白的功能特性进行有益的比较，这可能有助于深入了解其他复杂蛋白质拓扑结构的产生。
