Molecular cloning and functional expression of a skeletal muscle dihydropyridine receptor from Rana catesbeiana.
In skeletal muscle the dihydropyridine receptor is the voltage sensor for excitation-contraction coupling and an L-type Ca2+ channel. We cloned a dihydropyridine receptor (named Fgalpha1S) from frog skeletal muscle, where excitation-contraction coupling has been studied most extensively. Fgalpha1S contains 5600 base pairs coding for 1688 amino acids. It is highly homologous with, and of the same length as, the C-truncated form predominant in rabbit muscle. The primary sequence has every feature needed to be an L-type Ca2+ channel and a skeletal-type voltage sensor. Currents expressed in tsA201 cells had rapid activation (5-10 ms half-time) and Ca2+-dependent inactivation. Although functional expression of the full Fgalpha1S was difficult, the chimera consisting of Fgalpha1S domain I in the rabbit cardiac Ca channel had high expression and a rapidly activating current. The slow native activation is therefore not determined solely by the alpha1 subunit sequence. Its Ca2+-dependent inactivation strengthens the notion that in rabbit skeletal muscle this capability is inhibited by a C-terminal stretch (Adams, B., and Tanabe, T. (1997) J. Gen. Physiol. 110, 379-389). This molecule constitutes a new tool for studies of excitation-contraction coupling, gating, modulation, and gene expression.
Zhou
J
J
Department of Molecular Biophysics and Physiology, Rush University, Chicago, Illinois 60612, USA. Jingsong.zhou@mcmail.Vanderbilt.edu
Cribbs
L
L
Yi
J
J
Shirokov
R
R
Perez-Reyes
E
E
Ríos
E
E
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D020746:Calcium Channels, L-Type; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004095:Dihydropyridines / Q000378:metabolism; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D011892:Rana catesbeiana; D017386:Sequence Homology, Amino Acid; D014981:Xenopus
D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D018076:DNA, Complementary; D004095:Dihydropyridines; D012333:RNA, Messenger; C038806:1,4-dihydropyridine; D002118:Calcium