title: Dynamics of Golgi matrix proteins after the blockage of ER to Golgi transport.
abstract: When the ER to Golgi transport is blocked by a GTP-restricted mutant of Sar1p (H79G) in NRK-52E cells, most Golgi resident proteins are transported back into the ER. In contrast, the cis-Golgi matrix proteins GM130 and GRASP65 are retained in punctate cytoplasmic structures, namely Golgi remnants. Significant amounts of the medial-Golgi matrix proteins golgin-45, GRASP55 and giantin are retained in the Golgi remnants, but a fraction of these proteins relocates to the ER. Golgin-97, a candidate trans-Golgi network matrix protein, is retained in Golgi remnant-like structures, but mostly separated from GM130 and GRASP65. Interestingly, most Sec13p, a COPII component, congregates into larger cytoplasmic clusters soon after the microinjection of Sar1p(H79G), and these move to accumulate around the Golgi apparatus. Sec13p clusters remain associated with Golgi remnants after prolonged incubation. Electron microscopic analysis revealed that Golgi remnants are clusters of larger vesicles with smaller vesicles, many of which are coated. GM130 is mainly associated with larger vesicles and Sec13p with smaller coated vesicles. The Sec13p clusters disperse when p115 binding to the Golgi apparatus is inhibited. These results suggest that cis-Golgi matrix proteins resist retrograde transport flow and stay as true residents in Golgi remnants after the inhibition of ER to Golgi transport.
authors.affiliation: Molecular Biology Laboratory, Faculty of Pharmaceutical Sciences, and Cancer Research Institute, Kanazawa University, Kanazawa 920-0934.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Yoshimura
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Yamamoto
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Misumi
authors.forename: Miwa
authors.initials: M
authors.lastname: Sohda
authors.forename: Francis A
authors.initials: FA
authors.lastname: Barr
authors.forename: Gourou
authors.initials: G
authors.lastname: Fujii
authors.forename: Abbas
authors.initials: A
authors.lastname: Shakoori
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ohno
authors.forename: Katsuyoshi
authors.initials: K
authors.lastname: Mihara
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Nakamura
mesh_terms: D001324:Autoantigens; D001692:Biological Transport / Q000502:physiology; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism*; D008845:Microinjections; D008854:Microscopy, Electron; D020559:Monomeric GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D028861:Nuclear Pore Complex Proteins; D010957:Plasmids / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D033921:Vesicular Transport Proteins
chemical_list: D001324:Autoantigens; C097741:Golgin subfamily A member 2; D008565:Membrane Proteins; D028861:Nuclear Pore Complex Proteins; D011993:Recombinant Fusion Proteins; C079620:SEC13 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D020559:Monomeric GTP-Binding Proteins; C077395:SAR1 protein, S cerevisiae