A novel gene, STT4, encodes a phosphatidylinositol 4-kinase in the PKC1 protein kinase pathway of Saccharomyces cerevisiae

Soshi Yoshida, Yoshikazu Ohya, Mark Goebl, Akihiko Nakano, Yasuhiro Anraku

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Abstract

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 °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.

Original languageEnglish (US)
Pages (from-to)1166-1171
Number of pages6
JournalJournal of Biological Chemistry
Volume269
Issue number2
StatePublished - Jan 14 1994

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ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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