The yeast Ca(2+)-ATPase homologue, PMR1, is required for normal Golgi function and localizes in a novel Golgi-like distribution.
PMR1, a Ca(2+)-adenosine triphosphatase (ATPase) homologue in the yeast Saccharomyces cerevisiae localizes to a novel Golgi-like organelle. Consistent with a Golgi localization, the bulk of PMR1 comigrates with Golgi markers in subcellular fractionation experiments, and staining of PMR1 by indirect immunofluorescence reveals a punctate pattern resembling Golgi staining in yeast. ... However, PMR1 shows only partial colocalization with known Golgi markers, KEX2 and SEC7, in double-label immunofluorescence experiments. The effect of PMR1 on Golgi function is indicated by pleiotropic defects in various Golgi processes in pmr1 mutants, including impaired proteolytic processing of pro-alpha factor and incomplete outer chain glycosylation of invertase. Consistent with the proposed role of PMR1 as a Ca2+ pump, these defects are reversed by the addition of millimolar levels of extracellular Ca2+, suggesting that Ca2+ disposition is essential to normal Golgi function. Absence of PMR1 function partially suppresses the temperature-sensitive growth defects of several sec mutants, and overexpression of PMR1 restricts the growth of others. Some of these interactions are modulated by changes in external Ca2+ concentrations. These results imply a global role for Ca2+ in the proper function of components governing transit and processing through the secretory pathway.
Mesh Terms:
Amino Acid Sequence, Base Sequence, Biological Transport, Calcium-Transporting ATPases, Carboxypeptidases, Cathepsin A, Epitopes, Fungal Proteins, Genes, Fungal, Glycosylation, Golgi Apparatus, Hot Temperature, Mannose, Molecular Sequence Data, Mutation, Peptides, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Amino Acid Sequence, Base Sequence, Biological Transport, Calcium-Transporting ATPases, Carboxypeptidases, Cathepsin A, Epitopes, Fungal Proteins, Genes, Fungal, Glycosylation, Golgi Apparatus, Hot Temperature, Mannose, Molecular Sequence Data, Mutation, Peptides, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Mol. Biol. Cell
Date: Jun. 01, 1992
PubMed ID: 1379856
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