Progression of the stacked Golgi compartments in the yeast Saccharomyces cerevisiae by overproduction of GDP-mannose transporter.
The Golgi compartments of the yeast Saccharomyces cerevisiaeare dispersed within the cytoplasm, in contrast to the stacked cisternae in the mammalian cell, and consequently are observed as a punctate pattern by immunofluorescent staining of Golgi-marker proteins. The VIG4/VRG4 gene encodes the essential yeast GDP-mannose transporter, which is a polytopic membrane protein in the early and medial Golgi compartments. Upon overexpression of this gene by the aid of a strong promoter and multicopy vector, we found that stacked multivesicular structures, which resembled the cisternae of mammalian Golgi apparatus, had developed in S. cerevisiae. Immuno-electron microscopy showed that the GDP-mannose transporter was located on the stacked cisternae. Immuno-isolation and immunoblotting analyses of the vesicles showed that the overproduced GDP-mannose transporter also co-localized with the Golgi glycosyltransferases, but not with the ER- or late Golgi-marker proteins as in the control cell. We propose that the localization mechanism of the GDP-mannose transporter in the Golgi compartment would be efficient and hardly saturable, and therefore the overproduced protein induced a progression of Golgi-like compartments rather than being mislocalized in other compartments, such as the ER or a vacuole.
Hashimoto
Hitoshi
H
Department of Biotechnology, University of Tokyo, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan.
Abe
Masato
M
Hirata
Aiko
A
Noda
Yoichi
Y
Adachi
Hiroyuki
H
Yoda
Koji
K
D001692:Biological Transport; D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D016695:Glycosyltransferases / Q000378:metabolism; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D016253:Microscopy, Immunoelectron; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000378:metabolism
D002352:Carrier Proteins; C428326:GDP-mannose transporter; D016695:Glycosyltransferases