Use of phosphorofluoridate analogues of D-myo-inositol 1,4,5-trisphosphate to assess the involvement of ionic interactions in its recognition by the receptor and metabolising enzymes.
D-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] analogues fluoridated at 4- or 5-phosphate or both were analysed to assess the involvement of ionic interactions between the phosphates of Ins(1,4,5)P3 and the proteins that recognize it, such as metabolic enzymes and the InsP3 receptor. These analogues were effective in inhibiting type I Ins(1,4,5)P3 5-phosphatase activity with much the same potency as Ins(1,4,5)P3, although the enzyme showed a lower Km value as pH values increased. In contrast, the analogues were less potent ligands than Ins(1,4,5)P3 in both the assay of [3H]Ins(1,4,5)P3 binding to the receptors and the phosphorylation of [3H]Ins(1,4,5)P3 catalysed by Ins(1,4,5)P3 3-kinase. These results suggest that ionic interactions with the dianionic 4- and 5-phosphates of Ins(1,4,5)P3 are involved in recognition by the receptor and the kinase, but not by the phosphatase.
Department of Biochemistry, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
K
K
Yoshimura
Y
Y
Watanabe
C
C
Erneux
M
M
Hirata
D001667:Binding, Competitive; D015220:Calcium Channels / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D020128:Inhibitory Concentration 50; D015544:Inositol 1,4,5-Trisphosphate / Q000031:analogs & derivatives*; D053496:Inositol 1,4,5-Trisphosphate Receptors; D000072181:Inositol Polyphosphate 5-Phosphatases; D007477:Ions; D007531:Isoflurophate; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*
D015220:Calcium Channels; D004791:Enzyme Inhibitors; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007477:Ions; D018160:Receptors, Cytoplasmic and Nuclear; D007531:Isoflurophate; D015544:Inositol 1,4,5-Trisphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases