Synthesis and application of photoaffinity analogues of inositol 1,4,5-trisphosphate selectively substituted at the 1-phosphate group.
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Synthesis and application of photoaffinity analogues of inositol 1,4,5-trisphosphate selectively substituted at the 1-phosphate group. / Schäfer, R; Nehls-Sahabandu, M; Grabowsky, B; Dehlinger-Kremer, M; Schulz, I; Mayr, Georg W.
In: BIOCHEM J, Vol. 272, No. 3, 3, 1990, p. 817-825.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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T1 - Synthesis and application of photoaffinity analogues of inositol 1,4,5-trisphosphate selectively substituted at the 1-phosphate group.
AU - Schäfer, R
AU - Nehls-Sahabandu, M
AU - Grabowsky, B
AU - Dehlinger-Kremer, M
AU - Schulz, I
AU - Mayr, Georg W.
PY - 1990
Y1 - 1990
N2 - We have synthesized two photolabile arylazido-analogues of Ins(1,4,5)P3 selectively substituted at the 1-phosphate group for determination of Ins(1,4,5)P3-binding proteins. These two photoaffinity derivatives, namely N-(4-azidobenzoyl)aminoethanol-1-phospho-D-myo-inositol 4,5-bisphosphate (AbaIP3) and N-(4-azidosalicyl)aminoethanol-1-phospho-D-myo-inositol 4,5-bisphosphate (AsaIP3), bind to high affinity Ins(1,4,5)P3-specific binding sites at a 9-fold lower affinity (Kd = 66 and 70 nM) than Ins(1,4,5)P3 (Kd = 7.15 nM) in a fraction from rat pancreatic acinar cells enriched in endoplasmic reticulum (ER). Other inositol phosphates tested showed comparable (DL-myo-inositol 1,4,5-trisphosphothioate, Kd = 81 nM) or much lower affinities for the binding sites [Ins(1,3,4,5)P4, Kd = 4 microM; Ins(1,4)P2, Kd = 80 microM]. Binding of AbaIP3 was also tested on a microsomal preparation of rat cerebellum [Kd = 300 nM as compared with Ins(1,4,5)P3, Kd = 45 nM]. Ca2+ release activity of the inositol derivatives was tested with AbaIP3. It induced a rapid and concentration-dependent Ca2+ release from the ER fraction [EC50 (dose producing half-maximal effect) = 3.1 microM] being only 10-fold less potent than Ins(1,4,5)P3 (EC50 = 0.3 microM). From the two radioactive labelled analogues ([3H]AbaIP3 and 125I-AsIP3) synthesized, the radioiodinated derivative was used for photoaffinity labelling. It specifically labelled three proteins with apparent molecular masses of 49, 37 and 31 kDa in the ER-enriched fraction. By subfractionation of this ER-enriched fraction on a Percoll gradient the 37 kDa Ins(1,4,5)P3 binding protein was obtained in a membrane fraction which showed the highest effect in Ins(1,4,5)P3-inducible Ca2+ release (fraction P1). The other two Ins(1,4,5)P3-binding proteins, of 49 and 31 kDa, were obtained in fraction P2, in which Ins(1,4,5)P3-induced Ca2+ release was half of that obtained in fraction P1. We conclude from these data that the 37 kDa and/or the 49 and 31 kDa proteins are involved in Ins(1,4,5)P3-induced Ca2+ release from the ER of rat pancreatic acinar cells.
AB - We have synthesized two photolabile arylazido-analogues of Ins(1,4,5)P3 selectively substituted at the 1-phosphate group for determination of Ins(1,4,5)P3-binding proteins. These two photoaffinity derivatives, namely N-(4-azidobenzoyl)aminoethanol-1-phospho-D-myo-inositol 4,5-bisphosphate (AbaIP3) and N-(4-azidosalicyl)aminoethanol-1-phospho-D-myo-inositol 4,5-bisphosphate (AsaIP3), bind to high affinity Ins(1,4,5)P3-specific binding sites at a 9-fold lower affinity (Kd = 66 and 70 nM) than Ins(1,4,5)P3 (Kd = 7.15 nM) in a fraction from rat pancreatic acinar cells enriched in endoplasmic reticulum (ER). Other inositol phosphates tested showed comparable (DL-myo-inositol 1,4,5-trisphosphothioate, Kd = 81 nM) or much lower affinities for the binding sites [Ins(1,3,4,5)P4, Kd = 4 microM; Ins(1,4)P2, Kd = 80 microM]. Binding of AbaIP3 was also tested on a microsomal preparation of rat cerebellum [Kd = 300 nM as compared with Ins(1,4,5)P3, Kd = 45 nM]. Ca2+ release activity of the inositol derivatives was tested with AbaIP3. It induced a rapid and concentration-dependent Ca2+ release from the ER fraction [EC50 (dose producing half-maximal effect) = 3.1 microM] being only 10-fold less potent than Ins(1,4,5)P3 (EC50 = 0.3 microM). From the two radioactive labelled analogues ([3H]AbaIP3 and 125I-AsIP3) synthesized, the radioiodinated derivative was used for photoaffinity labelling. It specifically labelled three proteins with apparent molecular masses of 49, 37 and 31 kDa in the ER-enriched fraction. By subfractionation of this ER-enriched fraction on a Percoll gradient the 37 kDa Ins(1,4,5)P3 binding protein was obtained in a membrane fraction which showed the highest effect in Ins(1,4,5)P3-inducible Ca2+ release (fraction P1). The other two Ins(1,4,5)P3-binding proteins, of 49 and 31 kDa, were obtained in fraction P2, in which Ins(1,4,5)P3-induced Ca2+ release was half of that obtained in fraction P1. We conclude from these data that the 37 kDa and/or the 49 and 31 kDa proteins are involved in Ins(1,4,5)P3-induced Ca2+ release from the ER of rat pancreatic acinar cells.
M3 - SCORING: Zeitschriftenaufsatz
VL - 272
SP - 817
EP - 825
JO - BIOCHEM J
JF - BIOCHEM J
SN - 0264-6021
IS - 3
M1 - 3
ER -