Ca2(+)-mobilising properties of synthetic fluoro-analogues of myo-inositol 1,4,5-trisphosphate and their interaction with myo-inositol 1,4,5-trisphosphate 3-kinase and 5-phosphatase.
The ability of two fluoro-analogues of D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) to mobilize intracellular Ca2+ stores in SH-SY5Y neuroblastoma cells has been investigated. DL-2-deoxy-2-fluoro-scyllo-Ins(1,4,5)P3 (2F-Ins(1,4,5)P3) and DL-2,2-difluoro-2-deoxy-myo-Ins(1,4,5)P3 (2,2-F2-Ins(1,4,5)P3) were full agonists (EC50s 0.77 and 0.41 microM respectively) and slightly less potent than D-Ins(1,4,5)P3 (EC50 0.13 microM), indicating that the axial 2-hydroxyl group of Ins(1,4,5)P3 is relatively unimportant in receptor binding and stimulation of Ca2+ release. Both analogues mobilized Ca2+ with broadly similar kinetics and were substrates for Ins(1,4,5)P3 3-kinase but, qualitatively, were slightly poorer than Ins(1,4,5)P3. 2F-Ins(1,4,5)P3 was a weak substrate for Ins(1,4,5)P3 5-phosphatase but 2,2-F2-Ins(1,4,5)P3 was apparently not hydrolysed by this enzyme, although it inhibited its activity potently (Ki = 26 microM).
Safrany
S T
ST
Department of Pharmacology, University of Leicester, UK.
Sawyer
D
D
Wojcikiewicz
R J
RJ
Nahorski
S R
SR
Potter
B V
BV
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D015544:Inositol 1,4,5-Trisphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000072181:Inositol Polyphosphate 5-Phosphatases; D007700:Kinetics; D009447:Neuroblastoma; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor)
C066765:2,2-difluoro-2-deoxy-inositol 1,4,5-trisphosphate; C066764:2-deoxy-2-fluoroinositol 1,4,5-trisphosphate; D015544:Inositol 1,4,5-Trisphosphate; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D010744:Phosphoric Monoester Hydrolases; D000072181:Inositol Polyphosphate 5-Phosphatases; D002118:Calcium