Horne G, Maechling C, Fleig A, Hirata M, Penner R, Spiess B, Potter BVL. d-6-Deoxy-myo-inositol 1,3,4,5-tetrakisphosphate, a mimic of d-myo-inositol 1,3,4,5-tetrakisphosphate: biological activity and pH-dependent conformational properties.
Biochem Biophys Res Commun 2004;
320:1262-70. [PMID:
15249226 DOI:
10.1016/j.bbrc.2004.06.079]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2004] [Indexed: 10/26/2022]
Abstract
D-6-Deoxy-myo-inositol 1,3,4,5-tetrakisphosphate [D-6-deoxy-Ins(1,3,4,5)P(4)] 3 is a novel deoxygenated analogue of D-myo-inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P(4)] 2, a central and enigmatic molecule in the polyphosphoinositide pathway of cellular signalling. D-6-Deoxy-Ins(1,3,4,5)P(4) is a moderate inhibitor of Ins(1,4,5)P(3) 5-phosphatase [1.8microM] compared to Ins(1,3,4,5)P(4) [0.15microM] and similar to that of L-Ins(1,3,4,5)P(4) [1.8microM]. In displacement of [(3)H] Ins(1,4,5)P(3) from the rat cerebellar Ins(1,4,5)P(3) receptor, while slightly weaker [IC(50)=800nM] than that of D-Ins(1,3,4,5)P(4) [IC(50)=220nM], 3 is less markedly different and again similar to that of L-Ins(1,3,4,5)P(4) [IC(50)=660nM]. 3 is an activator of I(CRAC) when inward currents are measured in RBL-2H3-M1 cells using patch-clamp electrophysiological techniques with a facilitation curve different to that of Ins(1,3,4,5)P(4). Physicochemical properties were studied by potentiometric (31)P and (1)H NMR titrations and were similar to those of Ins(1,3,4,5)P(4) apart from the observation of a biphasic titration curve for the P1 phosphate group. A novel vicinal phosphate charge-induced conformational change of the inositol ring above pH 10 was observed for D-6-deoxy-Ins(1,3,4,5)P(4) that would normally be hindered because of the central stabilising role played by the 6-OH group in Ins(1,3,4,5)P(4). We conclude that the 6-OH group in Ins(1,3,4,5)P(4) is crucial for its physicochemical behaviour and biological properties of this key inositol phosphate.
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