McGovern K, Ehrmann M, Beckwith J
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.
EMBO J. 1991 Oct;10(10):2773-82. doi: 10.1002/j.1460-2075.1991.tb07826.x.
We have used genetic methods to investigate the role of the different domains of a bacterial cytoplasmic membrane protein, MalF, in determining its topology. This was done by analyzing the effects of MalF topology of deleting various domains of the protein using MalF-alkaline phosphatase fusion proteins. Our results show that the cytoplasmic domains of the protein are the pre-eminent topogenic signals. These domains contain information that determines their cytoplasmic location and, thus, the orientation of the membrane spanning segments surrounding them. Periplasmic domains do not appear to have equivalent information specifying their location and membrane spanning segments do not contain information defining their orientation in the membrane. The strength of cytoplasmic domains as topogenic signals varies, correlated with the density of positively charged amino acids within them.
我们已采用遗传学方法来研究细菌细胞质膜蛋白MalF的不同结构域在确定其拓扑结构中所起的作用。这是通过分析使用MalF-碱性磷酸酶融合蛋白删除该蛋白各个结构域对MalF拓扑结构的影响来实现的。我们的结果表明，该蛋白的细胞质结构域是主要的拓扑信号。这些结构域包含决定其细胞质定位的信息，进而决定围绕它们的跨膜片段的方向。周质结构域似乎没有指定其位置的等效信息，跨膜片段也不包含确定其在膜中方向的信息。细胞质结构域作为拓扑信号的强度各不相同，这与其中带正电荷氨基酸的密度相关。
