title: Biogenesis of a novel compartment for autophagosome-mediated unconventional protein secretion.
abstract: The endoplasmic reticulum (ER)-Golgi-independent, unconventional secretion of Acb1 requires many different proteins. They include proteins necessary for the formation of autophagosomes, proteins necessary for the fusion of membranes with the endosomes, proteins of the multivesicular body pathway, and the cell surface target membrane SNARE Sso1, thereby raising the question of what achieves the connection between these diverse proteins and Acb1 secretion. In the present study, we now report that, upon starvation in Saccharomyces cerevisiae, Grh1 is collected into unique membrane structures near Sec13-containing ER exit sites. Phosphatidylinositol 3 phosphate, the ESCRT (endosomal sorting complex required for transport) protein Vps23, and the autophagy-related proteins Atg8 and Atg9 are recruited to these Grh1-containing membranes, which lack components of the Golgi apparatus and the endosomes, and which we call a novel compartment for unconventional protein secretion (CUPS). We describe the cellular proteins required for the biogenesis of CUPS, which we believe is the sorting station for Acb1's release from the cells.
authors.affiliation: Department of Cell and Developmental Biology, Centre for Genomic Regulation, 08003 Barcelona, Spain.
authors.forename: Caroline
authors.initials: C
authors.lastname: Bruns
authors.forename: J Michael
authors.initials: JM
authors.lastname: McCaffery
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Curwin
authors.forename: Juan M
authors.initials: JM
authors.lastname: Duran
authors.forename: Vivek
authors.initials: V
authors.lastname: Malhotra
mesh_terms: D001343:Autophagy / Q000502:physiology*; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D010588:Phagosomes; D050600:SNARE Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: C492820:ACB1 protein, S cerevisiae; C113757:ATG8 protein, S cerevisiae; C434065:ATG9 protein, S cerevisiae; D000071190:Autophagy-Related Protein 8 Family; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C554600:Grh1 protein, S cerevisiae; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D028861:Nuclear Pore Complex Proteins; C079620:SEC13 protein, S cerevisiae; D050600:SNARE Proteins; C425333:STP22 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins