L-type calcium channels: binding domains for dihydropyridines and benzothiazepines are located in close proximity to each other

The binding of a fluorescent diltiazem analogue (3R,4S)-cis-1- 2- 3- 3- 4,4-difluoro-3a,4-dihydro-5,7-dimethyl-4-bora-3a,4 a-diaza-s-indacen-3-yl propionyl amino ethyl -1,3,4,5-tetrahydro-3-hydroxy-4 -(4-methoxyphenyl)-6-(trifluoromethyl)-2H-1-benzazepin-2-one to L-type Ca2+ channels in the presence of 1,4-dihydropyridines has been investigated. The results showed that the binding domains of these drugs are localized in close proximity to each other on the extracellular side of the channel.