title: L-myo-inositol 1,4,5,6-tetrakisphosphate (3-hydroxy)kinase.
abstract: Homogenates of primary-cultured murine bone macrophages contain an enzyme capable of synthesizing myo-[3H]inositol pentakisphosphate from myo-[3H]inositol tetrakisphosphate fractions derived from myo-[3H]inositol-labelled mouse macrophages and chick erythrocytes. D-myo-inositol 1,3,4,5-tetrakis[32P]-phosphate present in the same incubations was not phosphorylated. Since the myo-[3H]inositol-labelled tetrakisphosphate fractions used as substrates consist of a mixture of L-myo-inositol 1,4,5,6-tetrakisphosphate (60-85%) and a periodate-resistant tetrakisphosphate(s) whose characteristics are consistent with those of D-myo-inositol 1,3,4,5-tetrakisphosphate (the preceding paper [Stephens, Hawkins, Carter, Chahwala, Morris, Whetton & Downes (1988) Biochem. J. 249, 271-282] ), these data suggest the existence of a kinase that phosphorylates L-myo-inositol 1,4,5,6-tetrakisphosphate to give a myo-inositol pentakisphosphate. A similar activity was identified in homogenates of rat cerebrum, liver, heart and parotid gland. D-myo-Inositol 1,3,4,5-tetrakis[32P]phosphate in the same incubations was not a substrate. The activity was almost entirely soluble in all the tissues investigated and was found at its greatest specific activity in brain cytosol. The activity was purified 120-fold from a rat brain homogenate by (NH4)2SO4 fractionation and anion-exchange chromatography. The activity was clearly distinct from D-myo-inositol 1,4,5-trisphosphate (3-hydroxy)kinase. Incubation of this partially purified preparation with L-myo-[3H]inositol 1,4,5,6-tetrakisphosphate from chick erythrocytes and [gamma-32P]ATP resulted in the formation of L-myo-[3H]-inositol [1-32P]1,3,4,5,6-pentakisphosphate. The enzyme is therefore identified as an L-myo-inositol 1,4,5,6-tetrakisphosphate (3-hydroxy)kinase.
authors.affiliation: Smith, Kline and French Research Ltd., Welwyn, Herts, U.K.
authors.forename: L R
authors.initials: LR
authors.lastname: Stephens
authors.forename: P T
authors.initials: PT
authors.lastname: Hawkins
authors.forename: A J
authors.initials: AJ
authors.lastname: Morris
authors.forename: P C
authors.initials: PC
authors.lastname: Downes
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D003600:Cytosol / Q000201:enzymology; D004912:Erythrocytes / Q000201:enzymology; D007295:Inositol Phosphates / Q000096:biosynthesis* / Q000378:metabolism; D008264:Macrophages / Q000201:enzymology; D051379:Mice; D010770:Phosphotransferases / Q000302:isolation & purification / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor); D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013403:Sugar Phosphates / Q000096:biosynthesis*; D014018:Tissue Distribution
chemical_list: D007295:Inositol Phosphates; D013403:Sugar Phosphates; C081655:inositol-1,3,4,5-tetrakisphosphate; C081651:inositol-1,4,5,6-tetrakisphosphate; C013571:inositol pentaphosphate; D010770:Phosphotransferases; D017853:Phosphotransferases (Alcohol Group Acceptor); C054930:inositol-tetrakisphosphate 3-kinase