inositol-3-4-5-trisphosphate and inositol-3-4-5-6-tetrakisphosphate

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.

Topics: Amino Acid Sequence; Genes, Plant; Glycine max; Inositol Phosphates; Molecular Sequence Data; Phosphorylation; Phosphotransferases (Alcohol Group Acceptor); Phytic Acid; Plant Proteins; Recombinant Proteins; Signal Transduction

Synthetic routes to various inositol polyphosphates have been discovered utilizing catalytic enantioselective and site-selective phosphorylation reactions. The syntheses described herein exploit a common intermediate to gain efficient access to eight unique inositol polyphosphates.

Topics: Catalysis; Chemistry, Organic; Inositol Phosphates; Phosphorylation; Polyphosphates; Stereoisomerism