A novel gene, STT4, encodes a phosphatidylinositol 4-kinase in the PKC1 protein kinase pathway of Saccharomyces cerevisiae.
A staurosporine-sensitive mutation (stt1) in yeast has been found in the PKC1 gene that encodes a protein kinase C homologue (Yoshida, S., Ikeda, E., Uno, I., and Mitsuzawa, H. (1992) Mol. Gen. Genet. 231, 337-344). We report here another staurosporine-sensitive mutant, stt4, which shows very similar phenotypes to that of the stt1 mutant. The stt4 temperature-sensitive mutant arrests mostly in G2/M phase at 37 degrees C, and the stt4 deletion mutant shows an osmoremedial phenotype. Staurosporine sensitivity of the stt4 mutant was suppressed by overexpression of PKC1/STT1, indicating genetic interaction between stt4 and pkc1/stt1. The nucleotide sequence of STT4 predicts a hydrophilic protein composed of 1,900 amino acid residues, with 26% sequence identity to the yeast VPS34 gene product and 27% to the catalytic subunit of mammalian phosphatidylinositol (PI) 3-kinase, respectively. Cell homogenates of the stt4 deletion mutant show normal PI3-kinase activity but lack most of the PI4-kinase activity that is detected in the wild-type. We conclude that STT4 encodes a yeast PI4-kinase that functions in the PKC1 protein kinase pathway.
Yoshida
S
S
Department of Biology, Faculty of Science, University of Tokyo, Japan.
Ohya
Y
Y
Goebl
M
M
Nakano
A
A
Anraku
Y
Y
D019870:1-Phosphatidylinositol 4-Kinase; D000595:Amino Acid Sequence; D001483:Base Sequence; D002874:Chromosome Mapping; D005656:Fungal Proteins / Q000235:genetics; D005800:Genes, Fungal; D016153:Genes, Suppressor; D005816:Genetic Complementation Test; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics*; D011493:Protein Kinase C / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; D046911:Macromolecular Substances; D029701:Saccharomyces cerevisiae Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; C441760:PIK1 protein, S cerevisiae; D011493:Protein Kinase C