title: Mapping of dihydropyridine binding residues in a less sensitive invertebrate L-type calcium channel (LCa v 1).
abstract: Invertebrate L-type calcium channel, LCa(v) 1, isolated from the pond snail Lymnaea stagnalis is nearly indistinguishable from mammalian Ca(v) 1.2 (α1C) calcium channel in biophysical characteristics observed in vitro. These L-type channels are likely constrained within a narrow range of biophysical parameters to perform similar functions in the snail and mammalian cardiovascular systems. What distinguishes snail and mammalian L-type channels is a difference in dihydropyridine sensitivity: 100 nM isradipine exhibits a significant block of mammalian Ca(v) 1.2 currents without effect on snail LCa(v)1 currents. The native snail channel serves as a valuable surrogate for validating key residue differences identified from previous experimental and molecular modeling work. As predicted, three residue changes in LCa(v)1 (N_3o18, F_3i10, and I_4i12) replaced with DHP-sensing residues in respective positions of Ca(v) 1.2, (Q_3o18, Y_3i10, and M_4i12) raises the potency of isradipine block of LCa(v)1 channels to that of mammalian Ca(v) 1.2. Interestingly, the single N_3o18_Q mutation in LCa(v) 1 channels lowers DHP sensitivity even further and the triple mutation bearing enhanced isradipine sensitivity, still retains a reduced potency of agonist, (S)-Bay K8644.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, Canada.
authors.forename: Adriano
authors.initials: A
authors.lastname: Senatore
authors.forename: Adrienne
authors.initials: A
authors.lastname: Boone
authors.forename: Stanley
authors.initials: S
authors.lastname: Lam
authors.forename: Taylor F
authors.initials: TF
authors.lastname: Dawson
authors.forename: Boris
authors.initials: B
authors.lastname: Zhorov
authors.forename: J David
authors.initials: JD
authors.lastname: Spafford
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001703:Biophysics / Q000379:methods; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000737:chemistry / Q000235:genetics*; D004095:Dihydropyridines / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D017275:Isradipine / Q000494:pharmacology; D007700:Kinetics; D008195:Lymnaea; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data
chemical_list: D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D004095:Dihydropyridines; C419385:L-type calcium channel alpha(1C); D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C038806:1,4-dihydropyridine; D017275:Isradipine