Cyclic AMP-dependent phosphorylation and regulation of the cardiac dihydropyridine-sensitive Ca channel.
A polyclonal antibody, CR2, prepared using the C-terminal peptide of the alpha 1 subunit of the rabbit cardiac DHP-sensitive Ca channel, specifically immunoprecipitated the [3H]PN200-110-labeled Ca channel solubilized from cardiac microsomes. The antibody recognized 250 and 200-kDa cardiac microsomal proteins as determined by immunoblotting, and cAMP-dependent protein kinase phosphorylated the 250-kDa, but not the 200-kDa protein in vitro. CHO cells, transfected with the cardiac alpha 1 subunit cDNA carried by an expression vector, synthesized a 250-kDa protein which was recognized by CR2. Adding db-cAMP or forskolin to the transformed CHO cells induced phosphorylation of the 250-kDa protein and stimulated the DHP-sensitive Ba current under patch-clamp conditions. These results suggested that the cardiac DHP-sensitive Ca channel was regulated by cAMP-dependent phosphorylation of the alpha 1 subunit.
Yoshida
A
A
Mitsubishi Kasei Institute of Life Sciences, Tokyo, Japan.
Takahashi
M
M
Nishimura
S
S
Takeshima
H
H
Kokubun
S
S
D000818:Animals; D016466:CHO Cells; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism*; D004095:Dihydropyridines / Q000494:pharmacology*; D015151:Immunoblotting; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011817:Rabbits
D015220:Calcium Channels; D004095:Dihydropyridines; D005576:Colforsin; C038806:1,4-dihydropyridine; D000242:Cyclic AMP