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Regulation of a liver plasma membrane phosphoinositide phosphodiesterase by guanine nucleotides and calcium
Author(s) -
Uhing Ronald J.,
Jiang Hang,
Prpic Veronica,
Exton John H.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80394-x
Subject(s) - phosphatidylinositol , gtp' , nucleotide , guanine , chemistry , nucleoside , biochemistry , phosphodiesterase , inositol , membrane , nucleoside diphosphate kinase , phosphatidylinositol 4,5 bisphosphate , receptor , signal transduction , enzyme , gene
Rat liver plasma membranes are enriched in a Ca 2+ ‐dependent phosphodiesterase active on phosphatidylinositol 4,5‐P 2 and phosphatidylinositol 4‐P, but not phosphatidylinositol. Inositol‐P 3 is the first product of the reaction, but is rapidly degraded. Micromolar concentrations of GTP and its nonhydrolyzable analogues stimulate the reaction, whereas GDP, GMP and other nucleoside triphosphates are inactive. GTP and its analogues decrease the requirement of the reaction for Ca 2+ and also increase its activity at saturating Ca 2+ . These results support the hypothesis that guanine nucleotides and a guanine nucleotide binding regulatory protein are involved in coupling the receptors for Ca 2+ ‐mediated agonists to the breakdown of plasma membrane phosphatidylinositol 4,5‐P 2 .