Abstract
Carboxypeptidase Y is a vacuolar enzyme from Saccharomyces cerevisiae. It enters the vacuole as a zymogen, procarboxypeptidase Y, which is immediately processed in a reaction involving two endoproteases, proteinase A and proteinase B. We have investigated the in vitro activation of purified procarboxypeptidase Y by purified proteinase A. This has identified two different processing intermediates; one active and one inactive. The intermediates define a 33 amino acid segment of the 91 amino acid propeptide as sufficient for maintaining the enzyme in an inactive state. The inactive intermediate was isolated from a processing reaction at neutral pH. In order to investigate the influence of vacuolar pH on processing in vivo, the autoactivation of proteinase A and its processing of procarboxypeptidase Y were studied in a vma2 prb1 mutant, which is deficient in vacuolar acidification and proteinase B activity. Efficient processing of procarboxypeptidase Y in the absence of proteinase B is dependent on acidic vacuolar pH, and the processing at neutral pH is slow and takes place in two steps similar to those identified in vitro.
| Original language | English |
|---|---|
| Journal | European Journal of Biochemistry |
| Volume | 220 |
| Issue number | 1 |
| Pages (from-to) | 19-27 |
| Number of pages | 9 |
| ISSN | 0014-2956 |
| Publication status | Published - 1994 |
Keywords
- Amino Acid Sequence
- Aspartic Acid Endopeptidases
- Binding Sites
- Carboxypeptidases
- Cathepsin A
- Enzyme Activation
- Enzyme Precursors
- Genes, Fungal
- Hydrogen-Ion Concentration
- Molecular Sequence Data
- Mutation
- Protein Processing, Post-Translational
- Saccharomyces cerevisiae
- Saccharomyces cerevisiae Proteins
- Serine Endopeptidases
- Vacuoles