Rothman J H, Hunter C P, Valls L A, Stevens T H
Proc Natl Acad Sci U S A. 1986 May;83(10):3248-52. doi: 10.1073/pnas.83.10.3248.
Using an immunological screening procedure that allows the detection of yeast cells aberrantly secreting vacuolar proteins, we have isolated a cloned DNA fragment containing the structural gene for the vacuolar enzyme proteinase A (PrA; EC 3.4.23.6). A large portion of PrA is misdirected to the cell surface in cells harboring the PrA structural gene on a multicopy plasmid. This mislocalized PrA traverses the late stages of the secretory pathway and differs slightly in apparent molecular weight from the vacuolar form. A deletion in the genomic copy of the PrA structural gene eliminates immunoreactive PrA as well as the enzymatic activities of at least three other vacuolar hydrolases. In the case of the vacuolar enzyme carboxypeptidase Y (EC 3.4.16.1), the lack of activity is due to the absence of proteolytic activation of the zymogen. Thus, PrA may be required for in vivo processing of a number of yeast vacuolar hydrolases.
通过一种免疫筛选程序，该程序能够检测异常分泌液泡蛋白的酵母细胞，我们分离出了一个克隆的DNA片段，其包含液泡酶蛋白酶A（PrA；EC 3.4.23.6）的结构基因。在多拷贝质粒上携带PrA结构基因的细胞中，大部分PrA被错误引导至细胞表面。这种错误定位的PrA穿过分泌途径的后期阶段，其表观分子量与液泡形式略有不同。PrA结构基因的基因组拷贝中的缺失消除了免疫反应性PrA以及至少其他三种液泡水解酶的酶活性。就液泡酶羧肽酶Y（EC 3.4.16.1）而言，活性的缺乏是由于酶原缺乏蛋白水解激活。因此，PrA可能是许多酵母液泡水解酶体内加工所必需的。
