Project Details
Description
The phosphorylation of phosphatidylinositol by the reaction sequence
phosphatidylinositol - phosphatidylinositol 4-phosphate -
phosphatidylinositol 4, 5-bisphosphate is regulated in the yeast
Saccharomyces cervisiae. Phosphatidylinositol 4, 5-bisphosphate, or its
breakdown products diacylglycerol and inositol trisphosphate, play an
essential role in S. cerevisiae cell proliferation.
Phosphatidylinositol kinase is the first enzyme in the phosphorylation
pathway of phosphatidylinositol. The regulation of this enzyme should
therefore play a major role in phosphatidylinositol metabolism and cell
growth in S. cerevisiae. Regulation of phosphatidylinositol kinase by
cAMP-dependent protein kinase will be examined in vitro and in vivo. In
vitro phosphorylation of phosphatidylinositol kinase and the effects of
phosphorylation of enzyme activity and kinetics will be examined using
pure phosphatidylinositol kinase. In vivo phosphorylation of
phosphatidylinositol kinase will be examined in wild-type and mutants
defective in cAMP-dependent protein kinase activity. The effects of
phosphatidylinositol kinase phosphorylation on phosphatidylinositol
metabolism and on overall phospholipid biosynthesis will be examined.
Systematic studies are proposed to examine the effects of phospholipid
composition and acyl moiety of the membrane on phosphatidylinositol
kinase activity. The effects of the acyl composition of the substrate
PI on activity will also be examined. These studies will be performed
with pure enzyme reconstituted into unilamellar phospholipid vesicles.
The reconstitution studies will be complemented with studies using a
Triton X-100-phospholipid mixed micelle system. The regulation
phosphatidylinositol kinase activity, subunit, and mRNA levels will be
examined in response to inositol and the growth phase. We will also
initiate a project to clone the structural gene for phosphatidylinositol
kinase using specific antibodies to the enzyme and a lambda gt11
expression vector library. The essential nature of PI kinase will also
be addressed. The results of the proposed studies should be relevant to
higher eucaryotic organisms.
Status | Finished |
---|---|
Effective start/end date | 1/1/90 → 6/30/95 |
Funding
- National Institute of General Medical Sciences
ASJC
- Chemistry(all)
- Cell Biology
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