Characterization of Grp1p, a novel cis-Golgi matrix protein.
A high copy suppressor screen with sec34-2, a temperature-sensitive mutant defective in the late stages of ER to Golgi transport, has resulted in the identification of a novel gene called GRP1 (also called RUD3). GRP1 encodes a hydrophilic yeast protein related to the mammalian Golgi matrix protein golgin-160. A large ... portion of the protein is predicted to form a coiled-coil structure. Although GRP1 is not essential for growth, the loss of Grp1p results in a growth defect at high temperature. GRP1 genetically interacts with several genes involved in vesicle targeting/fusion stages of ER to Golgi transport. Despite these interactions, pulse chase analysis using Grp1p-depleted cells did not reveal a significant delay in the transit of the vacuolar protease carboxypeptidase Y. Grp1p-depleted cells efficiently secreted invertase which was underglycosylated, suggesting some disturbance of Golgi function. Grp1p-GFP predominantly colocalizes with the cis-Golgi marker Och1p. Despite lacking a signal peptide and a significant stretch of hydrophobic amino acids, Grp1p pellets with membranes. It is extracted with 1M NaCl or 0.1M Na(2)CO(3) (pH 11.0), but is surprisingly insoluble in 1% Triton X-100. Grp1p does not recycle to the ER when forward transport is blocked and a cis-Golgi marker (Och1p-HA), but not a trans-Golgi marker (Chs5p-HA), became dispersed in grp1 Delta cells after 1.5h incubation at 38.5 degrees C. Together, these data suggest that Grp1p is a novel matrix protein that is involved in the structural organization of the cis-Golgi.
Mesh Terms:
Carrier Proteins, Cell Division, Cell Membrane, Detergents, Endoplasmic Reticulum, Glycoside Hydrolases, Glycosylation, Golgi Apparatus, Green Fluorescent Proteins, Luminescent Proteins, Mannosyltransferases, Membrane Glycoproteins, Membrane Proteins, Microscopy, Fluorescence, Octoxynol, Peptides, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Subcellular Fractions, Temperature, Time Factors, Vesicular Transport Proteins, beta-Fructofuranosidase
Carrier Proteins, Cell Division, Cell Membrane, Detergents, Endoplasmic Reticulum, Glycoside Hydrolases, Glycosylation, Golgi Apparatus, Green Fluorescent Proteins, Luminescent Proteins, Mannosyltransferases, Membrane Glycoproteins, Membrane Proteins, Microscopy, Fluorescence, Octoxynol, Peptides, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Subcellular Fractions, Temperature, Time Factors, Vesicular Transport Proteins, beta-Fructofuranosidase
Biochem. Biophys. Res. Commun.
Date: Mar. 28, 2003
PubMed ID: 12646213
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