3-Position modification of myo-inositol 1,4,5-trisphosphate: consequences for intracellular Ca2+ mobilisation and enzyme recognition

Stephen T. Safrany, Robert A. Wilcox, Changsheng Liu, Barry V.L. Potter, Stefan R. Nahorski

Research output: Contribution to journalArticlepeer-review

41 Citations (Scopus)

Abstract

The ability of the novel D-myo-inositol 1,4,5-trisphosphate (Ins(1,4,5)P3) analogues, L-chiro-inositol 2,3,5-trisphosphate (L-ch-Ins(2,3,5)P3) and D-3-deoxy-3-fluoro-myo-inositol 1,4,5-trisphophate (3F-Ins(1,4,5)P3), to bind to the Ins(1,4,5)P3 receptor, mobilise intracellular Ca2+ stores and interact with metabolic enzymes has been investigated. L-ch-Ins(2,3,5)P3 and 3F-Ins(1,4,5)P3 were bound by the Ins(1,4,5)P3 receptor from bovine adrenal cortex with relatively high affinity (Ki values 60.4 and 8.0 nM respectively) but with lower affinity than Ins(1,4,5)P3 (KD = 5.9 nM). Both analogues were apparent full agonists at the Ca2+ mobilising receptor in SH-SY5Y cells, but were less potent than Ins(1,4,5)P3 (EC50 L-ch-Ins(2,3,5)P3 = 1.4 μM,F-Ins(1,4,5)P3 = 0.37 μM and Ins(1,4,5)P3 = 0.12 μM). L-ch-Ins(2,3,5)P3 and 3F-Ins(1,4,5)P3 were resistant to Ins(1,4,5)P3 3-kinase, and were potent inhibitors of the enzyme (Ki values 7.1 and 8.6 μM respectively). 3F-Ins(1,4,5)P3 was hydrolysed by Ins(1,4,5)P3 5-phosphatase at a similar rate to Ins(1,4,5)P3, but inhibited dephosphorylation of [3H]Ins(1,4,5)P3 with high potency (apparent Ki = 3.9 μM) L-ch-Ins(2,3,5)P3 was also recognised by the enzyme with high affinity (Ki = 7.7 μM) but was resistant to hydrolysis. These results suggest that the environment around C-3 is of major importance for recognition not only by Ins(1,4,5)P3 3-kinase but also by Ins(1,4,5)P3 5-phosphatase.

Original languageEnglish
Pages (from-to)265-272
Number of pages8
JournalEuropean Journal of Pharmacology: Molecular Pharmacology
Volume226
Issue number3
DOIs
Publication statusPublished - 1 Jul 1992
Externally publishedYes

Keywords

  • Ca mobilization
  • Inositol phosphate analogues
  • Second messenger

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