Phosphatidate phosphatase from Saccharomyces cerevisiae: Isolation of 45- and 104-kDa forms of the enzyme that are differentially regulated by inositol

K. R. Morlock, J. J. McLaughlin, Y. P. Lin, G. M. Carman

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Abstract

Immunoblot analysis of cell extracts using antibodies specific for the 91-kDa form of membrane-associated phosphatidate phosphatase from Saccharomyces cerevisiae (Lin, Y.-P., and Carman, G.M. (1989) J. Biol. Chem. 264, 8641-8645) revealed the existence of a 45-kDa form of the enzyme. Immunoblot analysis also showed that the 91-kDa form of the enzyme was a proteolytic product of a 104-kDa enzyme. The mitochondrial fraction contained the 45-kDa enzyme, whereas the microsomal fraction contained the 45- and 104-kDa enzymes. In vivo labeling experiments showed that the 104-kDa form of phosphatidate phosphatase was not a precursor of the 45-kDa form of the enzyme. The 45- and 104-kDa forms of phosphatidate phosphatase were purified and characterized. The enzymological properties of both enzymes were similar. However, the phosphatidate phosphatase 45- and 104-kDa proteins differed with respect to their isoelectric points and peptide fragments resulting from V8 proteolysis and cyanogen bromide cleavage. The expression of the phosphatidate phosphatase 45- and 104-kDa enzymes were regulated differentially in cells supplemented with inositol. The addition of inositol to the growth medium resulted in the induction of the phosphatidate phosphatase 45-kDa enzyme. The expression of the 104-kDa enzyme was not affected by inositol. Both forms of phosphatidate phosphatase were induced when cells entered the stationary phase of growth.

Original languageEnglish (US)
Pages (from-to)3586-3593
Number of pages8
JournalJournal of Biological Chemistry
Volume266
Issue number6
StatePublished - 1991

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Biochemistry
  • Cell Biology

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