The dihydropyridine Ca2+antagonist drugs used in the therapy of cardiovacular disorders inhibitl-type Ca2+ channels by binding to a single high affinity site. Photoaffinity labeling and analysis of mutant Ca2+ channels implicate the IIIS6 and IVS6 segments in high affinity binding. The amino acid residues that are required for high affinity binding of dihydropyridine Ca2+ channel antagonists were probed by alanine-scanning mutagenesis of the α1C subunit, transient expression in mammalian cells, and analysis by measurements of ligand binding and block of Ba2+ currents through expressed Ca2+ channels. Eleven amino acid residues in transmembrane segments IIIS6 and IVS6 were identified whose mutation reduced the affinity for the Ca2+ antagonist PN200-110 by 2–25-fold. Both amino acid residues conserved among Ca2+ channels and those specific to l-type Ca2+ channels were found to be required for high affinity dihydropyridine binding. In addition, mutation F1462A increased the affinity for the dihydropyridine Ca2+ antagonist PN200-110 by 416-fold with no effect on the affinity for the Ca2+ agonist Bay K8644. The residues in transmembrane segments IIIS6 and IVS6 that are required for high affinity binding are primarily aligned on single faces of these two α helices, supporting a “domain interface model” of dihydropyridine binding and action in which the IIIS6 and IVS6 interact to form a high affinity dihydropyridine receptor site on l-type Ca2+ channels.
Analysis of the Dihydropyridine Receptor Site ofl-type Calcium Channels by Alanine-scanning Mutagenesis*
B. Peterson,Barry D. Johnson,G. Hockerman,Matthew Acheson,T. Scheuer,W. Catterall
Published 1997 in Journal of Biological Chemistry
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- Publication year
1997
- Venue
Journal of Biological Chemistry
- Publication date
1997-07-25
- Fields of study
Biology, Medicine, Chemistry
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Semantic Scholar, PubMed
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