Ruohola H, Ferro-Novick S
Department of Cell Biology, Yale University School of Medicine, New Haven, CT 06510.
Proc Natl Acad Sci U S A. 1987 Dec;84(23):8468-72. doi: 10.1073/pnas.84.23.8468.
The sec53 mutant is a conditional lethal yeast secretory mutant. At 37 degrees C, precursors to exported proteins become firmly attached to the endoplasmic reticulum membrane and are not released into the lumen in a soluble form. The accumulated precursors are insoluble in the detergent Triton X-100; however, urea, a known protein denaturant, solubilizes them. Using antibody directed against the Sec53 protein, we found that a substantial portion of the Sec53 protein is associated with the cytoplasmic surface of the endoplasmic reticulum membrane. Membrane-bound Sec53 protein is largely insoluble in Triton X-100, but the protein is effectively released from the membrane by urea. We propose that the Sec53 protein may be a member of a complex of proteins required for an early step in protein processing and transport.
sec53突变体是一种条件致死型酵母分泌突变体。在37摄氏度时，分泌蛋白的前体牢固地附着在内质网膜上，无法以可溶形式释放到内腔中。积累的前体不溶于去污剂Triton X-100；然而，已知的蛋白质变性剂尿素可使其溶解。使用针对Sec53蛋白的抗体，我们发现相当一部分Sec53蛋白与内质网膜的细胞质表面相关联。膜结合的Sec53蛋白在很大程度上不溶于Triton X-100，但该蛋白可通过尿素有效地从膜上释放出来。我们提出，Sec53蛋白可能是蛋白质加工和运输早期步骤所需的蛋白质复合物的成员。
