Aux1p/Swa2p is required for cortical endoplasmic reticulum inheritance in Saccharomyces cerevisiae

• Published in: Molecular biology of the cell Vol. 12; no. 9; pp. 2614 - 2628
• Main Authors: Du, Y, Pypaert, M, Novick, P, Ferro-Novick, S
• Format: Journal Article
• Language: English
• Published: United States American Society for Cell Biology 01-09-2001
• Subjects: ADP-Ribosylation Factor 1 - genetics; ADP-Ribosylation Factor 1 - metabolism; Amino Acid Sequence; Base Sequence; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Division; Cell Membrane - metabolism; Cell Membrane - ultrastructure; Cloning, Molecular; Endoplasmic Reticulum - metabolism; Endoplasmic Reticulum - ultrastructure; Extrachromosomal Inheritance; Microscopy, Electron; Microscopy, Fluorescence; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation - genetics; Phosphoproteins - chemistry; Phosphoproteins - genetics; Phosphoproteins - metabolism; Protein Structure, Tertiary; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - ultrastructure; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Vacuoles - metabolism; Vacuoles - ultrastructure; Vesicular Transport Proteins
• ISSN: 1059-1524; 1939-4586
• DOI: 10.1091/mbc.12.9.2614

In the yeast Saccharomyces cerevisiae, the endoplasmic reticulum (ER) is found at the periphery of the cell and around the nucleus. The segregation of ER through the mother-bud neck may occur by more than one mechanism because perinuclear, but not peripheral ER, requires microtubules for this event. To identify genes whose products are required for cortical ER inheritance, we have used a Tn3-based transposon library to mutagenize cells expressing a green fluorescent protein-tagged ER marker protein (Hmg1p). This approach has revealed that AUX1/SWA2 plays a role in ER inheritance. The COOH terminus of Aux1p/Swa2p contains a J-domain that is highly related to the J-domain of auxilin, which stimulates the uncoating of clathrin-coated vesicles. Deletion of the J-domain of Aux1p/Swa2p leads to vacuole fragmentation and membrane accumulation but does not affect the migration of peripheral ER into daughter cells. These findings suggest that Aux1p/Swa2p may be a bifunctional protein with roles in membrane traffic and cortical ER inheritance. In support of this hypothesis, we find that Aux1p/Swa2p localizes to ER membranes.