期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1981
卷号：78
期号：1
页码：435-439
DOI：10.1073/pnas.78.1.435
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Carboxypeptidase Y, a vacuolar enzyme in Saccharomyces cerevisiae, is synthesized as a larger precursor whose apparent molecular mass is approximately 67,000 daltons. We have characterized a recessive mutation, pep4-3, that prevents maturation of this precursor. The accumulated precursor does not possess enzymatic activity. We have shown that the precursor accumulating in the pep4-3 mutant is not produced in a doubly mutant strain that also bears a mutation in the carboxypeptidase Y structural gene that eliminates production of carboxypeptidase Y. We have also shown that a nonsense fragment of carboxypeptidase Y is processed. Although there is evidence that proteinase B can catalyze the conversion of the precursor to a mature form in vitro, nonsense mutations in the structural gene for proteinase B, PRB1, do not affect the levels of carboxypeptidase Y activity, and strains bearing these mutations produce a carboxypeptidase Y of apparently normal size. Hence, proteinase B is not essential for the maturation of carboxypeptidase Y precursor in vivo. The pep4-3 mutation affects at least five vacuolar enzymes. This suggests that there is a processing event common to all of these enzymes.
