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.
Mesh Terms:
1-Phosphatidylinositol 4-Kinase, Amino Acid Sequence, Base Sequence, Chromosome Mapping, Fungal Proteins, Genes, Fungal, Genes, Suppressor, Genetic Complementation Test, Macromolecular Substances, Molecular Sequence Data, Mutagenesis, Insertional, Phosphotransferases (Alcohol Group Acceptor), Protein Kinase C, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment, Sequence Homology, Amino Acid
J. Biol. Chem.
Date: Jan. 14, 1994
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