Borel A C, Simon S M
Laboratory of Cellular Biophysics, Rockefeller University, New York, New York 10021, USA.
Biochemistry. 1996 Aug 20;35(33):10587-94. doi: 10.1021/bi960950q.
The initial steps in the biogenesis of membrane proteins parallel those of secretory proteins. However, membrane proteins contain a signal to stop translocation across the membrane. For polytopic membrane proteins, those with multiple transmembrane segments, little is known of the temporal sequence or relationship between synthesis of the nascent proteins, translocation, folding, and integration of the membrane segments into the bilayer. Here we demonstrate that latent membrane segments translocate sequentially as they emerge from the ribosome and do not accumulate on the cytosolic side to form loops, or larger structures, prior to translocation across the membrane.
膜蛋白生物合成的起始步骤与分泌蛋白的起始步骤相似。然而，膜蛋白含有一个停止跨膜转运的信号。对于多聚体膜蛋白，即那些具有多个跨膜区段的膜蛋白，对于新生蛋白的合成、转运、折叠以及膜区段整合到双层膜中的时间顺序或相互关系，我们知之甚少。在此，我们证明潜在的膜区段在从核糖体出现时会依次转运，并且在跨膜转运之前不会在胞质侧积累形成环或更大的结构。
