title: Differential stereoselectivity of D- and L-myo-inositol 1,2,4, 5-tetrakisphosphate binding to the inositol 1,4,5-trisphosphate receptor and 3-kinase.
abstract: D- and L-myo-inositol 1,2,4,5-tetrakisphosphate (Ins(1,2,4,5)P(4)) were investigated for their ability to bind to the D-myo-inositol 1, 4,5-trisphosphate (Ins(1,4,5)P(3)) receptor in a bovine adrenal cortical membrane fraction, to mobilize intracellular Ca(2+) stores in Xenopus oocytes, and to bind to the rat brain Ins(1,4,5)P(3) 3-kinase overexpressed and purified in E. coli. In competitive binding experiments with the Ins(1,4,5)P(3) receptor, D-Ins(1,2,4, 5)P(4) effectively displaced [(3)H]Ins(1,4,5)P(3) in a concentration-dependent manner with a potency comparable to that of D-Ins(1,4,5)P(3), while L-Ins(1,2,4,5)P(4) was approximately 50-fold less effective than D-Ins(1,4,5)P(3) and D-Ins(1,2,4,5)P(4). The DL-Ins(1,2,4,5)P(4) racemate bound to the Ins(1,4,5)P(3) receptor with an apparent intermediate efficiency. Injection of D-Ins(1,2,4, 5)P(4) into oocytes evoked a chloride current dependent on intracellular Ca(2+) mobilization in which the agonists ranked in a similar order of potency as in the Ins(1,4,5)P(3) receptor binding. On the other hand, D-Ins(1,2,4,5)P(4) only inhibited the binding of [(3)H]Ins(1,4,5)P(3) to 3-kinase very weakly with a markedly reduced potency compared to D-Ins(1,4,5)P(3), indicating that D-Ins(1,2,4, 5)P(4) is not an effective competitor in the phosphorylation of [(3)H]-Ins(1,4,5)P(3) by 3-kinase. The results, therefore, clearly indicate that D-Ins(1,2,4,5)P(4) is as effective as D-Ins(1,4,5)P(3) in the binding to the receptor but not 3-kinase, and access of Ins(1, 2,4,5)P(4) over the Ins(1,4,5)P(3) receptor calls for stringent stereospecificity with D-Ins(1,2,4,5)P(4) being the active form in DL-Ins(1,2,4,5)P(4)-mediated Ca(2+) mobilization.
authors.affiliation: Department of Life Science, Division of Molecular and Life Science, Pohang University of Science and Technology, Pohang, South Korea.
authors.forename: B C
authors.initials: BC
authors.lastname: Suh
authors.forename: M J
authors.initials: MJ
authors.lastname: Kim
authors.forename: G
authors.initials: G
authors.lastname: Choi
authors.forename: K Y
authors.initials: KY
authors.lastname: Choi
authors.forename: J K
authors.initials: JK
authors.lastname: Han
authors.forename: S K
authors.initials: SK
authors.lastname: Chung
authors.forename: K T
authors.initials: KT
authors.lastname: Kim
mesh_terms: D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002417:Cattle; D005260:Female; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism*; D009865:Oocytes; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D013237:Stereoisomerism; D014981:Xenopus
chemical_list: D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D018160:Receptors, Cytoplasmic and Nuclear; C116606:inositol-1,2,4,5-tetrakisphosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase; D002118:Calcium