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[ 3 H]9‐Methyl‐7‐bromoeudistomin D, a caffeine‐like powerful Ca 2+ releaser, binds to caffeine‐binding sites distinct from the ryanodine receptors in brain microsomes
Author(s) -
Yoshikawa Kazumori,
Furukawa Ken-Ichi,
Yamamoto Masayuki,
Momose Kazutaka,
Ohizumi Yasushi
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01021-6
Subject(s) - ryanodine receptor , caffeine , endoplasmic reticulum , binding site , microsome , chemistry , biophysics , biochemistry , stereochemistry , biology , enzyme , endocrinology
[ 3 H]9‐Methyl‐7‐bromoeudistomin D ([ 3 H]MBED), the most powerful Ca 2+ releaser from sarcoplasmic reticulum, specifically bound to the brain microsomes. Caffeine competitively inhibited [ 3 H]MBED binding. [ 3 H]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 [ 3 H]ryanodine binding. The profile of sucrose‐density gradient centrifugation of solubilized microsomes indicated that [ 3 H]MBED binding protein was different from [ 3 H]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.