Ca<sup>2+</sup>-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
Safrany ST., Sawyer D., Wojcikiewicz RJH., Nahorski SR., Potter BVL.
The ability of two fluoro-analogues of D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P 3 ) to mobilize intracellular Ca 2+ stores in SH-SY5Y neuroblastoma cells has been investigated. DL-2-deoxy-2-fluoro-scyllo-Ins(1,4,5)P 3 (2F-Ins(1,4,5)P 3 ) and DL-2,2-difluoro-2-deoxy-myo-Ins(1,4,5)P 3 (2,2-F 2 -Ins(1,4,5)P 3 ) were full agonists (EC 50 s 0.77 and 0.41 μM respectively) and slightly less potent than D-Ins(1,4,5)P 3 (EC 50 0.13 μM), indicating that the axial 2-hydroxyl group of Ins(1,4,5)P 3 is relatively unimportant in receptor binding and stimulation of Ca 2+ release. Both analogues mobilized Ca 2+ with broadly similar kinetics and were substrates for Ins(1,4,5)P 3 3-kinase but, qualitatively, were slightly poorer than Ins(1,4,5)P 3 . 2F-Ins(1,4,5)P 3 was a weak substrate for Ins(1,4,5)P 3 5-phosphatase but 2,2-F 2 -Ins(1,4,5)P 3 was apparently not hydrolysed by this enzyme, although it inhibited its activity potently (K i = 26 μM). © 1990.