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Metabolic and signaling properties of an Itpk gene family in Glycine max
Author(s) -
Stiles Amanda R.,
Qian Xun,
Shears Stephen B.,
Grabau Elizabeth 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.2008.04.054
Subject(s) - glycine , recombinant dna , gene , biochemistry , phosphorylation , chemistry , inositol , kinase , biology , genetics , amino acid , receptor
We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P 3 5/6‐kinase activity, but a kinetic analysis raised questions about its biological significance. Instead, we provide evidence that one alternative biological role for soybean Itpks is to interconvert the Cl − channel inhibitor, Ins(3,4,5,6)P 4 , and its metabolic precursor, Ins(1,3,4,5,6)P 5 , within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P 3 to Ins(1,3,4,6)P 4 which was further phosphorylated to Ins(1,3,4,5,6)P 5 by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid‐independent pathway of InsP 6 synthesis.