Figure 1.

(A) Schematic representation of chimera AL1 (13) and derived mutants F4A-IF19,20AA. Repeats I and II were from the α_1A subunit. L-type sequences that were inserted into the carp skeletal muscle α_1S are shown as black transmembrane segments (IIIS6 and IVS6) with bold lines as adjacent S5-S6 connecting loops. (B) Sequence alignment (Lower) of transmembrane segments IIIS6 of chimera AL1 (the carp skeletal muscle α_1S, see 33) and segments IIIS6 of the cardiac L-type α_1C (34) and the class A α_1A subunit (15). Homologous putative pore-orientated phenylalanines in segment IIIS6 of AL1 and alanine mutations are highlighted. (C) Schematic α-helical representation of amino acid sequence of repeat IIIS6 of chimera AL1 (shaded). Substituted putative pore-orientated amino acids of mutants F4A-F20A that are homologous between α_1A and α_1C are shown (solid).