title: Apg2 is a novel protein required for the cytoplasm to vacuole targeting, autophagy, and pexophagy pathways.
abstract: To survive starvation conditions, eukaryotes have developed an evolutionarily conserved process, termed autophagy, by which the vacuole/lysosome mediates the turnover and recycling of non-essential intracellular material for re-use in critical biosynthetic reactions. Morphological and biochemical studies in Saccharomyces cerevisiae have elucidated the basic steps and mechanisms of the autophagy pathway. Although it is a degradative process, autophagy shows substantial overlap with the biosynthetic cytoplasm to vacuole targeting (Cvt) pathway that delivers resident hydrolases to the vacuole. Recent molecular genetics analyses of mutants defective in autophagy and the Cvt pathway, apg, aut, and cvt, have begun to identify the protein machinery and provide a molecular resolution of the sequestration and import mechanism that are characteristic of these pathways. In this study, we have identified a novel protein, termed Apg2, required for both the Cvt and autophagy pathways as well as the specific degradation of peroxisomes. Apg2 is required for the formation and/or completion of cytosolic sequestering vesicles that are needed for vacuolar import through both the Cvt pathway and autophagy. Biochemical studies revealed that Apg2 is a peripheral membrane protein. Apg2 localizes to the previously identified perivacuolar compartment that contains Apg9, the only characterized integral membrane protein that is required for autophagosome/Cvt vesicle formation.
authors.affiliation: University of Michigan, Department of Biology, Ann Arbor, Michigan 48109, USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Kim
authors.forename: W P
authors.initials: WP
authors.lastname: Huang
authors.forename: H
authors.initials: H
authors.lastname: Abeliovich
authors.forename: P E
authors.initials: PE
authors.lastname: Stromhaug
authors.forename: W A
authors.initials: WA
authors.lastname: Dunn
authors.forename: D J
authors.initials: DJ
authors.lastname: Klionsky
mesh_terms: D000071183:Autophagy-Related Proteins; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry* / Q000494:pharmacology*; D005838:Genotype; D008565:Membrane Proteins / Q000737:chemistry; D008856:Microscopy, Fluorescence; D009584:Nitrogen / Q000378:metabolism; D020675:Peroxisomes / Q000378:metabolism*; D010587:Phagocytosis; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000378:metabolism; D013347:Subcellular Fractions; D013997:Time Factors; D014162:Transfection; D014617:Vacuoles / Q000378:metabolism*
chemical_list: C434064:ATG2 protein, S cerevisiae; C434065:ATG9 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D009584:Nitrogen