Characterization of an inositol 1,3,4,5-tetrakisphosphate 3-phosphatase from porcine brain.
Some of the properties of a high affinity Ins(1,3,4,5)P4 3-phosphatase (Km approximately 400 nM) from the soluble fraction of pig brain are presented. Several inositol polyphosphates reduced the activity of the Ins-(1,3,4,5)P4 3-phosphatase. The most effective inhibitors were Ins(1,3,4, 5,6)P5 and InsP6 with Ki-values of about 60 nM and 3 nM, respectively. We could show that at least InsP6 is a likely substrate of the Ins(1,3,4,5)P4 3-phosphatase, which degraded InsP6 with a very low reaction velocity. This 3-phosphatase may be important for the metabolism of higher phos-phorylated inositol polyphosphates.
Höer
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A
Institut für Pharmakologie, Freien Universität, Berlin.
Oberdisse
E
E
D000818:Animals; D001921:Brain / Q000201:enzymology*; D003600:Cytosol / Q000201:enzymology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007295:Inositol Phosphates / Q000378:metabolism / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013379:Substrate Specificity; D013552:Swine
D007295:Inositol Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; D015544:Inositol 1,4,5-Trisphosphate; D010744:Phosphoric Monoester Hydrolases; C064119:multiple inositol-polyphosphate phosphatase