Affordable Access

Publisher Website

Phosphatidylinositol 4-kinases inSaccharomyces cerevisiae

Authors
Identifiers
DOI: 10.1016/s1874-5245(96)80015-2
Disciplines
  • Biology
  • Chemistry

Abstract

Abstract Phosphatidylinositol 4-kinase from the yeast Saccharomyces cerevisiae catalyzes the formation of phosphatidylinositol 4-phosphate and ADP from phosphatidylinositol and ATP. Phosphatidylinositol 4-kinase catalyzes the first phosphorylation reaction in the reaction sequence phosphatidylinositol → phosphatidylinositol 4-phosphate → phosphatidylinositol 4,5-bisphosphate. This phosphorylation sequence in S. cerevisiae is regulated by glucose and sterol. Phosphatidylinositol 4,5-bisphosphate appears to play an essential role in cell proliferation of S. cerevisiae. Since phosphatidylinositol 4-kinase catalyzes the first step in the phosphorylation sequence of phosphatidylinositol, the enzyme should play a major role in phosphoinositide synthesis and cell growth in S. cerevisiae. Two membrane-associated (45 kDa and 55 kDa) forms and one cytosolic-associated (125 kDa) form of phosphatidylinositol 4-kinase have been purified and characterized from S. cerevisiae. The membrane-associated phosphatidylinositol 4-kinases differ with respect to their physiochemical, enzymological, and kinetic properties. The binding and catalytic steps of the reactions catalyzed by the membrane-associated phosphatidylinositol 4-kinases toward phosphatidylinositol has been been defined through meaningful kinetic analyses using Triton X-100/PI-mixed micelles. Detailed kinetic analyses of the inhibition of membrane-associated phosphatidylinositol 4-kinases by nucleotides has led to insights on the regulation of phosphoinositide synthesis in response to glucose.

There are no comments yet on this publication. Be the first to share your thoughts.