The inositol 1,4,5-trisphosphate (lnsP3) receptor was purified from bovine cerebellum and reconstituted in liposomes composed of phosphatidylcholine (PC) and phosphatidylethanola-mine (PE) (1:1) successfully. No effec...The inositol 1,4,5-trisphosphate (lnsP3) receptor was purified from bovine cerebellum and reconstituted in liposomes composed of phosphatidylcholine (PC) and phosphatidylethanola-mine (PE) (1:1) successfully. No effect of Ca2+ concentration on [3H]-lnsP3 binding to unreconsti-tuted lnsP3 receptor could be observed either at 4℃ or at 25℃, whereas the effect of [Ca2+] on reconstituted lnsP3 receptor depended on the temperature. The Ca2+ concentration outside the proteolipsome ([Ca2+]o) had no detectable effect on lnsP3 binding to lnsP3 receptor at 4℃. In contrast, with increase of [Ca2+]o from 0 to 100 nmol/L at 25℃, the lnsP3 binding activity increased gradually. Then the lnsP3 binding activity was decreased drastically at higher [Ca2+]0 and inhibited entirely at 50 nmol/L [Ca2+]. Conformational studies on intrinsic fluorescence of the reconstituted lnsP3 receptor and its quenching by Kl and HB indicated that the global conformation of reconstituted lnsP3 receptor could not be affected by [Ca2+]o展开更多
文摘The inositol 1,4,5-trisphosphate (lnsP3) receptor was purified from bovine cerebellum and reconstituted in liposomes composed of phosphatidylcholine (PC) and phosphatidylethanola-mine (PE) (1:1) successfully. No effect of Ca2+ concentration on [3H]-lnsP3 binding to unreconsti-tuted lnsP3 receptor could be observed either at 4℃ or at 25℃, whereas the effect of [Ca2+] on reconstituted lnsP3 receptor depended on the temperature. The Ca2+ concentration outside the proteolipsome ([Ca2+]o) had no detectable effect on lnsP3 binding to lnsP3 receptor at 4℃. In contrast, with increase of [Ca2+]o from 0 to 100 nmol/L at 25℃, the lnsP3 binding activity increased gradually. Then the lnsP3 binding activity was decreased drastically at higher [Ca2+]0 and inhibited entirely at 50 nmol/L [Ca2+]. Conformational studies on intrinsic fluorescence of the reconstituted lnsP3 receptor and its quenching by Kl and HB indicated that the global conformation of reconstituted lnsP3 receptor could not be affected by [Ca2+]o
