title: Auxilin facilitates membrane traffic in the early secretory pathway.
abstract: Coat protein complexes contain an inner shell that sorts cargo and an outer shell that helps deform the membrane to give the vesicle its shape. There are three major types of coated vesicles in the cell: COPII, COPI, and clathrin. The COPII coat complex facilitates vesicle budding from the endoplasmic reticulum (ER), while the COPI coat complex performs an analogous function in the Golgi. Clathrin-coated vesicles mediate traffic from the cell surface and between the trans-Golgi and endosome. While the assembly and structure of these coat complexes has been extensively studied, the disassembly of COPII and COPI coats from membranes is less well understood. We describe a proteomic and genetic approach that connects the J-domain chaperone auxilin, which uncoats clathrin-coated vesicles, to COPII and COPI coat complexes. Consistent with a functional role for auxilin in the early secretory pathway, auxilin binds to COPII and COPI coat subunits. Furthermore, ER-Golgi and intra-Golgi traffic is delayed at 15°C in swa2Δ mutant cells, which lack auxilin. In the case of COPII vesicles, we link this delay to a defect in vesicle fusion. We propose that auxilin acts as a chaperone and/or uncoating factor for transport vesicles that act in the early secretory pathway.
authors.affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093-0668.
authors.forename: Jingzhen
authors.initials: J
authors.lastname: Ding
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami, Miami, FL 33136.
authors.forename: Verónica A
authors.initials: VA
authors.lastname: Segarra
authors.affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093-0668.
authors.forename: Shuliang
authors.initials: S
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Huaqing
authors.initials: H
authors.lastname: Cai
authors.affiliation: Department of Molecular and Cellular Pharmacology, University of Miami, Miami, FL 33136 sfnovick@ucsd.edu slemmon@med.miami.edu.
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Lemmon
authors.affiliation: Department of Cellular and Molecular Medicine, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093-0668 sfnovick@ucsd.edu slemmon@med.miami.edu.
authors.forename: Susan
authors.initials: S
authors.lastname: Ferro-Novick
mesh_terms: D034021:Auxilins / Q000235:genetics* / Q000378:metabolism*; D022181:COP-Coated Vesicles / Q000235:genetics / Q000378:metabolism; D002966:Clathrin / Q000378:metabolism; D022163:Clathrin-Coated Vesicles / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D021381:Protein Transport / Q000502:physiology; D040901:Proteomics; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D055571:Secretory Pathway / Q000502:physiology; D033921:Vesicular Transport Proteins / Q000378:metabolism
chemical_list: D034021:Auxilins; D002966:Clathrin; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins