FIGURE: 1 / 3
The members of the inositol hexakisphosphate kinase family, IP6K1 and IP6K2, have a high affinity and selectivity for inositol hexakisphosphate (InsP6) as a substrate. IP6K1 and IP6K2 (also designated PiUS) convert InsP6 to PP-InsP5. However, neither kinase demonstrates any catalytic activity with other inositol pyrophosphates. The presence of InsP6, which inhibits serine/threonine protein phosphatases, increases the influx of calcium across the plasma membrane and implies that it may mediate the regulation of insulin exocytosis. IP6K1 was purified as a 54 kDa protein in rat brain extracts. By homology, IP6K1 and IP6K2 were characterized in mouse as a 50 kDa and 49 kDa protein, respectively. IP6K1 displays ATP synthase activity by transferring a phosphate from PP-InsP5 to ADP, which suggests a role for the IP6 kinases as high energy phosphate donors.
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Protein Aliases: ATP:1D-myo-inositol-hexakisphosphate phosphotransferase; Inositol hexakisphosphate kinase 2; inositol hexaphosphate kinase 2; inositol-hexakisphosphate kinase; InsP6 kinase 2; IP6 Kinase; P(i)-uptake stimulator; pi uptake stimulator; PiUS
Gene Aliases: 1500005N04Rik; AW050208; IHPK2; IP6K2; PIUS; TCCCIA00113
Molecular Function: kinase