[3H]9‐Methyl‐7‐bromoeudistomin D, a caffeine‐like powerful Ca2+ releaser, binds to caffeine‐binding sites distinct from the ryanodine receptors in brain microsomes

[摘要]

[³H]9-Methyl-7-bromoeudistomin D ([³H]MBED), the most powerful Ca²⁺ releaser from sarcoplasmic reticulum, specifically bound to the brain microsomes. Caffeine competitively inhibited [³H]MBED binding. [³H]MBED binding was markedly blocked by procaine, whereas that was enhanced by adenosine-5′-(β,γ-methylene)triphosphate. The B _max value was 170 times more than that of [³H]ryanodine binding. The profile of sucrose-density gradient centrifugation of solubilized microsomes indicated that [³H]MBED binding protein was different from [³H]ryanodine binding protein. These results suggest that there are MBED/caffeine-binding sites in brain that are distinct from the ryanodine receptor and that MBED becomes an essential molecular probe for characterizing caffeine-binding protein in the central nervous system.

[学科分类] 生物化学/生物物理

[关键词] Caffeine;Ryanodine receptor;cGMP;Brain;9-Methyl-7-bromoeudistomin D;MBED;9-methyl-7-bromoeudistomin D;B max;amount of maximum bindingl K d dissociation constant;SR;sarcoplasmic reticulum;ER;endoplasmic reticulum;IP3;inositol 1;4;5-trisphosphate;CICR;Ca2+induced Ca2+ release;HEPES;2[4-(2-hydroxyethyl)-1-piperazinyllethanesulfonic acid;AMPPCP;adenosine-5′(β;γ-methyylene)triphosphate;PKG;cyclic GMP-dependent protein kinase