Inhibition of porcine brain inositol 1,3,4-trisphosphate kinase by inositol polyphosphates, other polyol phosphates, polyanions and polycations

Philip J. Hughes*, Christopher J. Kirk, Robert H. Michell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


We have partially purified an enzyme activity that phosphorylates inositol 1,3,4-trisphosphate from porcine brain, rat liver and bovine testis by FPLC chromatography on Q-Sepharose anion-exchange resin and Heparin-agarose. The products of this reaction were inositol 1,3,4,6-tetrakisphosphate and inositol 1,3,4,5-tetrakisphosphate. The same enzyme appears to be responsible for both 6-kinase and 5-kinase activities against inositol 1,3,4-trisphosphate (the 6-kinase: 5-kinase activity ratio is approximately 4 to 1), has a pH optimum of ∼ 6.8 and requires Mg2+ for activity. The Km values of the enzyme for inositol 1,3,4-trisphosphate and ATP were ∼ 0.5 μM and ∼ 100 μM, respectively. Inositol 3,4,5,6-tetrakisphosphate, inositol 1,3,4,6-tetrakisphosphate and inositol 1,3,4,5-tetrakisphosphate are all competitive inhibitors with Ki values of 0.4 μM, 3 μM and 5 μM, respectively, well within their likely intracellular concentration ranges: they inhibited 6-kinase and 5-kinase activities equally. 2,3-Bisphosphoglycerate and spermine were also competitive inhibitors, with Ki values of 0.8 mM and 12 mM, respectively. Dextran sulphate was a non-competitive inhibitor with a Ki of ∼ 15 μM, and poly-l-lysine (IC50 ∼ 200 μM), polyvinylsulphate (IC50 ∼ 250 μM) and heparin (IC50 ∼ 2 mg/ml) also inhibited. Inhibition by these compounds suggests that inositol 3,4,5,6-tetrakisphosphate (and to a lesser extent inositol 1,3,4,5-tetrakisphosphate and other naturally occurring intracellular ions) may restrict the synthesis of inositol 1,3,4,6-tetrakisphosphate and hence regulate the rate of inositol penta- and hexakisphosphate synthesis from receptorgenerated inositol phosphates.

Original languageEnglish
Pages (from-to)57-70
Number of pages14
JournalBBA - Molecular Cell Research
Issue number1
Publication statusPublished - 11 Aug 1994


  • Enzyme inhibition
  • Inositol 1,3,4-triphosphate kinase
  • Protein purification

ASJC Scopus subject areas

  • Biophysics
  • Cell Biology
  • Molecular Biology


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