Hirota J, Michikawa T, Miyawaki A, Takahashi M, Tanzawa K, Okura I, Furuichi T, Mikoshiba K
Department of Molecular Neurobiology, University of Tokyo, Japan.
FEBS Lett. 1995 Jul 17;368(2):248-52. doi: 10.1016/0014-5793(95)00659-w.
Kinetics of Ca2+ release by adenophostin, a novel agonist of inositol 1,4,5-trisphosphate (IP3) receptor, in the purified and reconstituted IP3 receptor type 1 (IP3R1) was investigated using the fluorescent Ca2+ indicator fluo-3. Submaximal concentrations of adenophostin caused quantal Ca2+ release from the purified IP3R1 as IP3 did. Adenophostin-induced Ca2+ release by the purified IP3R1 exhibited a high positive cooperativity (nH = 3.9 +/- 0.2, EC50 = 11 nM), whereas the IP3-induced Ca2+ release exhibited a moderate one (nH = 1.8 +/- 0.1, EC50 = 100 nM). Inhibition of [3H]IP3 binding to the purified IP3R1 by adenophostin exhibited a positive cooperativity (nH = 1.9, Ki = 10 nM), whereas IP3 did not (nH = 1.1, Ki = 41 nM).
利用荧光钙指示剂fluo-3研究了新型肌醇1,4,5-三磷酸（IP3）受体激动剂腺嘌呤磷素在纯化和重组的1型IP3受体（IP3R1）中释放Ca2+的动力学。亚最大浓度的腺嘌呤磷素与IP3一样，能引起纯化的IP3R1产生量子化Ca2+释放。纯化的IP3R1由腺嘌呤磷素诱导的Ca2+释放表现出高度正协同性（nH = 3.9 +/- 0.2，EC50 = 11 nM），而IP3诱导的Ca2+释放表现出中等协同性（nH = 1.8 +/- 0.1，EC50 = 100 nM）。腺嘌呤磷素对纯化的IP3R1结合[3H]IP3的抑制表现出正协同性（nH = 1.9，Ki = 10 nM），而IP3则没有（nH = 1.1，Ki = 41 nM）。
