Apg14p and Apg6/Vps30p Form a Protein Complex Essential for Autophagy in the Yeast, Saccharomyces cerevisiae

• Published in: The Journal of biological chemistry Vol. 273; no. 35; pp. 22284 - 22291
• Main Authors: Kametaka, Satoshi, Okano, Takafumi, Ohsumi, Mariko, Ohsumi, Yoshinori
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 28.08.1998; American Society for Biochemistry and Molecular Biology
• Subjects: 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
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.273.35.22284

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 theapg6-1 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 theapg14 null mutation affect the CPY sorting pathway. Structural analysis of APG6 revealed that APG6is 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.