Solanum tuberosum inositol phosphate kinase (StlTPK1) displaying inositol phosphate-inositol phosphate and inositol phosphate-ADP phosphotransferase activities

Samuel E. K. Caddick, Christopher J. Harrison, Ioanna Stavridou, Jennifer L. Mitchell, Andrew M. Hemmings, Charles A. Brearley

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17 Citations (Scopus)


We describe a multifunctional inositol polyphosphate kinase/phosphotransferase from Solanum tuberosum, StITPKa (GenBank accession number: EF362784), hereafter called StITPK1. StITPK1 displays inositol 3,4,5,6-tetrakisphosphate 1-kinase activity: Km = 27 µM, and Vmax = 19 nmol min-1 mg-1. The enzyme displays inositol 1,3,4,5,6-pentakisphosphate 1-phosphatase activity in the absence of a nucleotide acceptor and inositol 1,3,4,5,6-pentakisphosphate–ADP phosphotransferase activity in the presence of physiological concentrations of ADP. Additionally, StITPK1 shows inositol phosphate-inositol phosphate phosphotransferase activity. Homology modelling provides a structural rationale of the catalytic abilities of StITPK1. Inter-substrate transfer of phosphate groups between inositol phosphates is an evolutionarily conserved function of enzymes of this class.
Original languageEnglish
Pages (from-to)1731-1737
Number of pages7
JournalFEBS Letters
Issue number12
Publication statusPublished - 28 May 2008

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