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A Solanum tuberosum inositol phosphate kinase (StITPK1) displaying inositol phosphate–inositol phosphate and inositol phosphate–ADP phosphotransferase activities
Author(s) -
Caddick Samuel E.K.,
Harrison Christopher J.,
Stavridou Ioanna,
Mitchell Jennifer L.,
Hemmings Andrew M.,
Brearley Charles A.
Publication year - 2008
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2008.04.034
Subject(s) - inositol , biochemistry , polyphosphate , phosphotransferase , phosphate , inositol phosphate , chemistry , phosphofructokinase 2 , kinase , enzyme , phosphatase , biology , receptor
We describe a multifunctional inositol polyphosphate kinase/phosphotransferase from Solanum tuberosum , StITPKα (GenBank accession number: EF362784), hereafter called StITPK1. StITPK1 displays inositol 3,4,5,6‐tetrakisphosphate 1‐kinase activity: K m = 27 μM, and V max = 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.