AKAP79 increases the functional expression of skeletal muscle Ca2+ channels in Xenopus oocytes.
The actions of the kinase A anchoring protein, AKAP79, a key element in the regulation of the cardiac L-type Ca2+ channel, were assessed on skeletal muscle Ca2+ channels expressed in Xenopus oocytes. The channels were reconstituted by expressing the pore forming alpha1s subunit and its accessory subunits, alpha2-delta, beta, and gamma. We report, for the first time, that peak Ca2+ channel currents are greatly increased (3.5-fold) by AKAP79 when co-expressed with the truncated form of the alpha1s subunit. Immunoblots revealed that the increase in current amplitude is not accompanied by a corresponding increase in the membrane levels of the alpha1s subunit. This suggests that AKAP79 does not increase the trafficking of the channel. In addition, we show that the transcript of AKAP150, the rat ortholog of the human AKAP79, is expressed in rat skeletal muscle and propose that AKAP79/150 modulates Ca2+ channel function.
Department of Pharmacology, Centro de Investigación y de Estudios Avanzados del I.P.N., México DF 07360, Mexico.
Consuelo
C
Plata
Juan
J
Escamilla
Elba
E
Carrillo
José M
JM
Galindo
Gerardo
G
Gamba
María C
MC
García
Jorge A
JA
Sánchez
D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D004553:Electric Conductivity; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D018482:Muscle, Skeletal / Q000737:chemistry; D009865:Oocytes / Q000378:metabolism / Q000502:physiology; D018408:Patch-Clamp Techniques; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D014982:Xenopus laevis
D054758:A Kinase Anchor Proteins; C487775:AKAP5 protein, human; D048868:Adaptor Proteins, Signal Transducing; C415703:Akap5 protein, rat; D020746:Calcium Channels, L-Type; D002352:Carrier Proteins; D012333:RNA, Messenger