A novel pathway for the formation of phosphatidylinositol 3,4-bisphosphate. Phosphorylation of phosphatidylinositol 3-monophosphate by phosphatidylinositol-3-monophosphate 4-kinase
- Burroughs Wellcome Co., Research Triangle Park, NC (USA)
Three polyphosphoinositides containing phosphate at the D-3 position of the inositol ring can be generated in vitro by phosphorylation of phosphatidylinositol, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate by a phosphatidylinositol-3-kinase. An alternative pathway for in vivo synthesis of one of these lipids was recently suggested: phosphatidylinositol 3,4-bisphosphate could be produced by phosphorylation of phosphatidylinositol 3-phosphate at the D-4 position of the inositol ring. Here we demonstrate the presence of an enzyme in human platelets that phosphorylates (32P)phosphatidylinositol 3-phosphate to produce (32P)phosphatidylinositol 3,4-bisphosphate. This enzyme is Mg2(+)-dependent and its apparent molecular mass is approximately 150 kDa as estimated by sucrose gradient centrifugation and gel filtration chromatography. Unlike the major phosphatidylinositol-4-kinase in platelets that is stimulated by the detergent Nonidet P-40, the phosphatidylinositol-3-phosphate-4-kinase is inhibited by Nonidet P-40. Both activities are also differentiated by the action of adenosine. The discovery of this new enzyme raises the possibility that multiple pathways exists for generating D-3 phosphorylated phosphoinositides.
- OSTI ID:
- 6213494
- Journal Information:
- Journal of Biological Chemistry; (USA), Vol. 265:36; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOSPHOLIPIDS
METABOLISM
PHOSPHOTRANSFERASES
ENZYME ACTIVITY
ADENOSINE
BIOLOGICAL PATHWAYS
BLOOD PLATELETS
LIQUID COLUMN CHROMATOGRAPHY
MAN
PHOSPHORUS 32
PHOSPHORYLATION
TRACER TECHNIQUES
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BLOOD
BLOOD CELLS
BODY FLUIDS
CHEMICAL REACTIONS
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
ENZYMES
ESTERS
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPIDS
MAMMALS
MATERIALS
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PRIMATES
RADIOISOTOPES
RIBOSIDES
SEPARATION PROCESSES
TRANSFERASES
VERTEBRATES
550501* - Metabolism- Tracer Techniques