Referenced in: none

Automatically associated channels: Kir2.3

Title: Photoaffinity labeling of the purified skeletal muscle calcium antagonist receptor by a novel benzothiazepine, [3H]azidobutyryl diltiazem.

Authors: K Naito, E McKenna, A Schwartz, P L Vaghy

Journal, date & volume: J. Biol. Chem., 1989 Dec 15 , 264, 21211-4

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/2556399

Abstract
Previous photoaffinity-labeling studies with [3H]azidopine, (+) [3H]PN200-110, and [3H]LU 49888 have demonstrated that 1,4-dihydropyridines (nifedipine-like drugs) and phenylalkylamines (verapamil-like drugs) bind exclusively to the 165-kDa alpha 1 subunit of skeletal muscle calcium channels. However, it has not been conclusively determined whether benzothiazepines (diltiazem-like drugs), which represent the third group of calcium antagonists, also bind to the alpha 1 subunit. Here we report data obtained with a newly developed benzothiazepine photoaffinity probe, [3H]azidobutyryl diltiazem. This drug competes with diltiazem for the benzothiazepine-binding site and, in purified calcium channel preparations, specifically labels the 165-kDa polypeptide which does not change its electrophoretic mobility upon disulfide reduction. These data show that benzothiazepines, just like 1,4-dihydropyridines and phenylalkylamines, bind to the alpha 1 subunit of the skeletal muscle calcium channels.