Mueckler M, Lodish H F
Nature. 1986;322(6079):549-52. doi: 10.1038/322549a0.
Most eukaryotic secretory and membrane proteins insert co-translationally into the membrane of the rough endoplasmic reticulum (RER), and are targeted there by one or more NH2-terminal or internal signal sequences. However, little is known about the actual translocation and membrane integration processes. In particular, any energy requirements for targeting and integration have remained obscure because of the inability to uncouple the processes from concomitant protein synthesis. We recently showed that the human glucose transporter (GT), an integral membrane glycoprotein, can insert post-translationally into dog pancreatic microsomes with low but demonstrable efficiency in vitro, and that a fragment corresponding to the NH2-terminal 340 amino acids and 8 of the 12 membrane-spanning alpha-helixes of GT (GT-N) can insert with significantly greater efficiency. We report here that post-translational insertion of GT-N into pancreatic microsomes requires energy in the form of a phosphodiester bond, and suggest that co-translational insertion of proteins into the RER may also require energy independent of that used for polypeptide synthesis.
大多数真核生物的分泌蛋白和膜蛋白在翻译过程中插入糙面内质网（RER）膜，并通过一个或多个氨基末端或内部信号序列靶向到那里。然而，对于实际的转运和膜整合过程知之甚少。特别是，由于无法将这些过程与伴随的蛋白质合成解偶联，靶向和整合所需的任何能量需求仍然不清楚。我们最近表明，人葡萄糖转运蛋白（GT）是一种整合膜糖蛋白，在体外可以以低但可证明的效率在翻译后插入犬胰腺微粒体，并且对应于GT氨基末端340个氨基酸和12个跨膜α螺旋中的8个的片段（GT-N）可以以明显更高的效率插入。我们在此报告，GT-N在胰腺微粒体中的翻译后插入需要磷酸二酯键形式的能量，并表明蛋白质在翻译过程中插入RER也可能需要独立于多肽合成所用能量的能量。
