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pubmed:abstractText |
We have cloned and characterized four Itpk genes from soybean. All four recombinant Itpk proteins showed canonical Ins(1,3,4)P3 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)P4, and its metabolic precursor, Ins(1,3,4,5,6)P5, within a substrate cycle. The soybean Itpks also phosphorylated Ins(3,4,6)P3 to Ins(1,3,4,6)P4 which was further phosphorylated to Ins(1,3,4,5,6)P5 by soybean Ipk2. Thus, soybean Itpks may participate in an inositol lipid-independent pathway of InsP6 synthesis.
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pubmed:affiliation |
Department of Plant Pathology, Physiology and Weed Science, Virginia Polytechnic Institute and State University, 413 Price Hall, Blacksburg, VA 24061, USA.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, Non-P.H.S.,
Research Support, N.I.H., Intramural
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