Traxler B, Beckwith J
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, MA 02115.
Proc Natl Acad Sci U S A. 1992 Nov 15;89(22):10852-6. doi: 10.1073/pnas.89.22.10852.
The maltose transporter of Escherichia coli is a hetero-oligomeric complex located in the cytoplasmic membrane of the cell. The in vivo assembly of this complex has been examined by using an assay based on the proteolytic sensitivity of one of its components, MalF. Immediately after synthesis and insertion into the membrane, MalF is sensitive to exogenously added proteases. In a time- and complex assembly-dependent fashion, MalF becomes protease resistant. Using this assay, we show that MalF is inserted into the membrane independently of other components of the transport complex. The assembly of the maltose transport complex occurs subsequently from a pool of freely diffusing protein in the membrane. This assembly process is efficient and occurs with rapid kinetics.
大肠杆菌的麦芽糖转运体是一种位于细胞胞质膜中的异源寡聚复合物。通过基于其一个组分MalF的蛋白水解敏感性的检测方法，对该复合物的体内组装进行了研究。MalF在合成并插入膜后，立即对外源添加的蛋白酶敏感。以时间和复合物组装依赖的方式，MalF变得对蛋白酶具有抗性。利用该检测方法，我们表明MalF独立于转运复合物的其他组分插入膜中。麦芽糖转运复合物随后从膜中自由扩散的蛋白质池中组装而成。这个组装过程是高效的，并且以快速的动力学发生。
