Apg14p and Apg6/Vps30p form a protein complex essential for autophagy in the yeast, Saccharomyces cerevisiae.
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.
Kametaka
S
S
Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Okano
T
T
Ohsumi
M
M
Ohsumi
Y
Y
D000595:Amino Acid Sequence; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D001483:Base Sequence; D017931:DNA Primers; D004271:DNA, Fungal; D004705:Endocytosis; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D013347:Subcellular Fractions / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism
C114337:ATG 14 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D017931:DNA Primers; D004271:DNA, Fungal; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins