title: Activation of phosphatidylinositol-4-phosphate kinase in rat liver plasma membranes by polyamines.
abstract: The formation of phosphatidylinositol 4,5-bisphosphate (PIP2) from endogenous substrate in rat liver plasma membranes was stimulated approximately 3-fold by 1 mM spermine, with half-maximal effect at 0.2 mM polyamine. This effect of spermine was due to enhancement of phosphatidylinositol-4-phosphate kinase activity rather than to a decrease in degradation of PIP2 formed or the substrate phosphatidylinositol 4-phosphate (PIP). The stimulation of phosphatidylinositol-4-phosphate kinase by spermine decreased to half at physiological ionic strength, and was not affected appreciably by variations in the concentration of ATP and MgCl2. Among several di- and polyamines only spermine and spermidine were effective. Although spermine may cause aggregation of membrane vesicles, thereby potentially increasing substrate availability for phosphatidylinositol-4-phosphate kinase, our results do not support such an explanation for the enhancement in enzyme activity. Phosphatidylinositol kinase activity, contrary to phosphatidylinositol-4-phosphate kinase, was not stimulated appreciably by spermine.
authors.affiliation: Biochemistry, Chemical Centre, University of Lund, Sweden.
authors.forename: G A
authors.initials: GA
authors.lastname: Lundberg
authors.forename: R
authors.initials: R
authors.lastname: Sundler
authors.forename: B
authors.initials: B
authors.lastname: Jergil
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008274:Magnesium / Q000494:pharmacology; D015636:Magnesium Chloride; D008297:Male; D009994:Osmolar Concentration; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D011073:Polyamines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013096:Spermine / Q000494:pharmacology
chemical_list: D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D011073:Polyamines; C037178:phosphatidylinositol 4-phosphate; D015636:Magnesium Chloride; D013096:Spermine; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase; D008274:Magnesium