RRC ID 35469
Author Murakami A, Kimura K, Nakano A.
Title The inactive form of a yeast casein kinase I suppresses the secretory defect of the sec12 mutant. Implication of negative regulation by the Hrr25 kinase in the vesicle budding from the endoplasmic reticulum.
Journal J Biol Chem
Abstract Sec12p is the guanine nucleotide exchange factor of Sar1 GTPase and functions at the very upstream in the vesicle budding reactions from the endoplasmic reticulum (ER). We previously identified three yeast loci, RST1, RST2, and RST3, whose mutations suppressed the temperature-sensitive growth of the sec12-4 mutant (Nakano, A. (1996) J. Biochem. (Tokyo) 120, 642-646). In the present study, we cloned the wild-type RST2 gene by complementation of the cold-sensitive phenotype of the rst2-1 mutant. RST2 turned out to be identical to HRR25, a gene encoding a dual-specificity casein kinase I in yeast. The rst2-1 mutation, which is now renamed hrr25-2, was due to the T176I amino acid replacement in the kinase domain. This mutation remedied not only the temperature-sensitive growth but also the defect of ER-to-Golgi protein transport of sec12. Immunoprecipitation of the hemagglutinin-tagged Hrr25-2 protein and a subsequent protein kinase assay showed that the kinase activity of the mutant protein was markedly reduced. The overproduction of another kinase-minus mutant of Hrr25p (Hrr25p K38A) slightly suppressed the growth defect of sec12-4 as well. These observations suggest that the reduction of the kinase activity in the mutant protein is important for the suppression of sec12. We propose that Hrr25p negatively regulates the vesicle budding from the ER.
Volume 274(6)
Pages 3804-10
Published 1999-2-5
DOI 10.1074/jbc.274.6.3804
PMID 9920934
MeSH Amino Acid Sequence Base Sequence Casein Kinase I* Casein Kinases Cloning, Molecular DNA Primers Endoplasmic Reticulum / enzymology* Fungal Proteins / chemistry Fungal Proteins / genetics* Fungal Proteins / metabolism* Genetic Complementation Test Guanine Nucleotide Exchange Factors Membrane Glycoproteins / genetics* Molecular Sequence Data Mutagenesis, Site-Directed Protein Kinases / metabolism* Saccharomyces cerevisiae / enzymology* Saccharomyces cerevisiae Proteins* Sequence Homology, Amino Acid
IF 4.106
Times Cited 56
DNA material pAM5-2 (RDB08778) pAM6-2 (RDB08779) pAM4-1 (RDB08780) pAM8-2 (RDB08781) pAM2-326 (RDB08782) pAM1-5 (RDB08783) pAM1-2 (RDB08784) pAM8-1 (K38A) (RDB08785) pAM13-2 (RDB08786) pAM13-3 (RDB08787).