title: The significance of the 1-kinase/1-phosphatase activities of the PPIP5K family.
abstract: The inositol pyrophosphates (diphosphoinositol polyphosphates), which include 1-InsP7, 5-InsP7, and InsP8, are highly 'energetic' signaling molecules that play important roles in many cellular processes, particularly with regards to phosphate and bioenergetic homeostasis. Two classes of kinases synthesize the PP-InsPs: IP6Ks and PPIP5Ks. The significance of the IP6Ks - and their 5-InsP7product - has been widely reported. However, relatively little is known about the biological significance of the PPIP5Ks. The purpose of this review is to provide an update on developments in our understanding of key features of the PPIP5Ks, which we believe strengthens the hypothesis that their catalytic activities serve important cellular functions. Central to this discussion is the recent discovery that the PPIP5K is a rare example of a single protein that catalyzes a kinase/phosphatase futile cycle.
authors: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 101 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA. Electronic address: shears@niehs.nih.gov.
authors: Stephen B
authors: SB
authors: Shears
authors: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 101 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA.
authors: Brandi M
authors: BM
authors: Baughman
authors: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 101 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA.
authors: Chunfang
authors: C
authors: Gu
authors: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 101 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA.
authors: Vasudha S
authors: VS
authors: Nair
authors: Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, National Institutes of Health, 101 T.W. Alexander Drive, Research Triangle Park, NC, 27709, USA.
authors: Huanchen
authors: H
authors: Wang
mesh_terms: D017766:Acid Anhydride Hydrolases / Q000235:genetics / Q000378:metabolism*; D020816:Amino Acid Motifs; D004734:Energy Metabolism / Q000235:genetics; D005786:Gene Expression Regulation; D006801:Humans; D007295:Inositol Phosphates / Q000378:metabolism*; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010833:Phytic Acid / Q000378:metabolism*; D000072417:Protein Domains; D015398:Signal Transduction
chemical_list: D007295:Inositol Phosphates; C402123:inositol heptakisphosphate; D010833:Phytic Acid; D017856:Phosphotransferases (Phosphate Group Acceptor); C519580:PPIP5K1 protein, human; D017766:Acid Anhydride Hydrolases; C116368:diphosphoinositol polyphosphate phosphohydrolase