Detection of inositol 1,4,5-trisphosphate kinase in retina. A direct demonstration of phosphorylation of inositol 1,4,5-trisphosphate by ATP.
The metabolism of myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] consists of two pathways: dephosphorylation by 5-phosphomonoesterase(s) produces inositol 1,4-bisphosphate, and phosphorylation by Ins(1,4,5)P3 3-kinase yields inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4]. The requirements for Ins(1,4,5)P3 kinase activity in retina were characterized. Apparent Km values for ATP and Ins(1,4,5)P3 are 1.4 mM and 1.3 microM respectively. A direct demonstration of phosphorylation of Ins(1,4,5)P3 by [gamma-32P]ATP was achieved. Characterization of the 32P-labelled product revealed that it had the expected chromatographic and electrophoretic properties of Ins(1,3,4,5)P4.
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Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, TX 77030.
Anderson
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D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D004590:Electrophoresis, Paper; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism; D010766:Phosphorylation; D010770:Phosphotransferases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D012160:Retina / Q000201:enzymology*
D007295:Inositol Phosphates; D010710:Phosphates; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase