Mai1p is essential for maturation of proaminopeptidase I but not for autophagy

FEBS Lett. 2002 Feb 13;512(1-3):173-9. doi: 10.1016/s0014-5793(02)02252-4.


We here identify Mai1p, a homologue of the autophagy protein Aut10p, as a novel component essential for proaminopeptidase I (proAPI) maturation under non-starvation conditions. In mai1Delta cells mature vacuolar proteinases are detectable and vacuolar acidification is normal. In mai1Delta cells autophagy occurs, though at a somewhat reduced level. This is indicated by proAPI maturation during starvation and accumulation of autophagic bodies during starvation with phenylmethylsulfonyl fluoride. Homozygous diploid mai1Delta cells sporulate, but with a slightly reduced frequency. Biologically active Ha-tagged Mai1p, chromosomally expressed under its native promoter, is at least in part peripherally membrane-associated. In indirect immunofluorescence it localizes to the vacuolar membrane or structures nearby. In some cells Ha-tagged Mai1p appears concentrated at regions adjacent to the nucleus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Aminopeptidases / metabolism*
  • Autophagy / physiology*
  • Autophagy-Related Proteins
  • Cell Compartmentation
  • Endopeptidases / genetics
  • Endopeptidases / metabolism*
  • Membrane Proteins
  • Molecular Sequence Data
  • Protein Precursors / metabolism*
  • Saccharomyces cerevisiae
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Sequence Homology, Amino Acid
  • Vacuoles / enzymology


  • ATG18 protein, S cerevisiae
  • Autophagy-Related Proteins
  • Membrane Proteins
  • Protein Precursors
  • Saccharomyces cerevisiae Proteins
  • ATG21 protein, S cerevisiae
  • Endopeptidases
  • Aminopeptidases
  • proaminopeptidase I