Valls L A, Hunter C P, Rothman J H, Stevens T H
Cell. 1987 Mar 13;48(5):887-97. doi: 10.1016/0092-8674(87)90085-7.
We have isolated cis-acting mutations in the gene encoding the yeast vacuolar protein carboxypeptidase Y (CPY) that result in missorting and aberrant secretion of up to 95% of newly synthesized CPY. The CPY polypeptides synthesized by these mutants use the late secretory pathway to exit the cell, since the late-acting sec1 mutation prevents their secretion. The mutant versions of CPY are secreted as the proCPY zymogen and are enzymatically activatable in vivo and in vitro. All the mutations, including small deletions and an amino acid substitution, map to the amino-terminal propeptide region and define a discrete yeast vacuolar localization domain whose integrity is required for efficient sorting of the CPY zymogen. Thus, the N-terminal propeptide of CPY carries out at least three functions: it mediates translocation across the endoplasmic reticulum, renders the enzyme inactive during transit, and targets the molecule to the vacuole.
我们已经在编码酵母液泡蛋白羧肽酶Y（CPY）的基因中分离出顺式作用突变，这些突变导致高达95%新合成的CPY分选错误并异常分泌。这些突变体合成的CPY多肽利用晚期分泌途径排出细胞，因为晚期作用的sec1突变会阻止它们的分泌。CPY的突变体版本以proCPY酶原形式分泌，并且在体内和体外均可被酶激活。所有突变，包括小的缺失和一个氨基酸替换，都定位在氨基末端前肽区域，并定义了一个离散的酵母液泡定位结构域，其完整性是CPY酶原有效分选所必需的。因此，CPY的N末端前肽至少执行三种功能：介导跨内质网转运，在转运过程中使酶失活，并将分子靶向液泡。
