Apg14p and Apg6/Vps30p form a protein complex essential for autophagy in the yeast, Saccharomyces cerevisiae

J Biol Chem. 1998 Aug 28;273(35):22284-91. doi: 10.1074/jbc.273.35.22284.

Abstract

Mutation in the Saccharomyces cerevisiae APG14 gene causes a defect in autophagy. Cloning and structural analysis of the APG14 gene revealed that APG14 encodes a novel hydrophilic protein with a predicted molecular mass of 40.5 kDa, and that Apg14p has a coiled-coil motif at its N terminus region. We found that overproduction of Apg14p partially reversed the defect in autophagy induced by the apg6-1 mutation. The apg6-1 mutant was found to be defective not only in autophagy but also in sorting of carboxypeptidase Y (CPY), a vacuolar-soluble hydrolase, to the vacuole. However, overexpression of APG14 did not alter the CPY sorting defect of the apg6-1 mutant, nor did the apg14 null mutation affect the CPY sorting pathway. Structural analysis of APG6 revealed that APG6 is identical to VPS30, which is involved in a retrieval step of the CPY receptor, Vps10p, to the late-Golgi from the endosome (Seaman, M. N. J., Marcusson, E. G., Cereghino, J. L., and Emr, S. D. (1997) J. Cell Biol. 137, 79-92). Subcellular fractionation indicated that Apg14p and Apg6p peripherally associated with a membrane structure(s). Apg14p was co-immunoprecipitated with Apg6p, suggesting that they form a stable protein complex. These results imply that Apg6/Vps30p has two distinct functions in the autophagic process and the vacuolar protein sorting pathway. Apg14p may be a component specifically required for the function of Apg6/Vps30p through the autophagic pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Autophagy*
  • Autophagy-Related Proteins
  • Base Sequence
  • DNA Primers
  • DNA, Fungal
  • Endocytosis
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Genes, Fungal
  • Molecular Sequence Data
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Subcellular Fractions / metabolism
  • Vacuoles / metabolism

Substances

  • ATG 14 protein, S cerevisiae
  • Autophagy-Related Proteins
  • DNA Primers
  • DNA, Fungal
  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins