title: The bovine cardiac receptor for calcium channel blockers is a 195-kDa protein.
abstract: The cardiac receptor for calcium channel blockers was purified from bovine microsomal membranes which contained 235 +/- 33 fmol nimodipine-binding sites/mg protein (mean +/- SEM of nine preparations). To identify the receptor during the purification 20% of its binding sites were prelabeled with (+)[3H]PN200-110. The receptor was solubilized with 0.6% digitonin and was purified to a specific density of 157 pmol/mg using a combination of ion-exchange, wheat-germ-agglutinin-Sepharose chromatography and sucrose density gradient centrifugation. In the last sucrose gradient bound (+)[3H]PN200-110 comigrated with a 195-kDa protein. ( +/-)[3H]Azidopine and [3H]ludopamil, the photoaffinity ligands for the dihydropyridine and phenylalkylamine-binding site of the calcium channel, were incorporated specifically into the 195-kDa protein. These data indicate that the bovine cardiac receptor for calcium channel blockers is a 195-kDa protein. Its molecular mass suggests that the bovine cardiac receptor differs considerably from the rabbit skeletal muscle receptor protein for calcium channel blockers.
authors.affiliation: Institut für Physiologische Chemie, Medizinische Fakultät der Saarlandes, Homburg, Federal Republic of Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schneider
authors.forename: F
authors.initials: F
authors.lastname: Hofmann
mesh_terms: D000345:Affinity Labels; D000818:Animals; D002121:Calcium Channel Blockers / Q000378:metabolism*; D015220:Calcium Channels; D002417:Cattle; D002499:Centrifugation, Density Gradient; D002848:Chromatography, DEAE-Cellulose; D003720:Densitometry; D008861:Microsomes / Q000032:analysis; D009206:Myocardium / Q000032:analysis*; D011978:Receptors, Nicotinic / Q000302:isolation & purification*; D012995:Solubility
chemical_list: D000345:Affinity Labels; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D011978:Receptors, Nicotinic