Regulation by protein kinase-C of putative P-type Ca channels expressed in Xenopus oocytes from cerebellar mRNA.
Xenopus oocytes injected with rat cerebellar mRNA expressed functional voltage-dependent Ca channels detected as an inward Ba current (IBa). The pharmacological resistance to dihydropyridines and omega-conotoxin together with the blockade obtained with Agelenopsis aperta venom suggest that these channels could be somehow assimilated to P-type Ca channels. The precise nature of the transplanted Ca channels was assessed by hybrid-arrest experiments using a specific oligonucleotide antisense-derivated from the recently cloned alpha 1-subunit of P channels (BI-1 clone). In addition, we demonstrate that exogenous Ca channel activity was enhanced by two different PKC activators (a phorbol ester and a structural analog to diacylglycerol). The general electrophysiological and pharmacological properties of the stimulated Ca channels remain unchanged. This potentiation induced by PKC activators is antagonized by a PKC inhibitor (staurosporine) and by a monoclonal antibody directed against PKC. It is concluded that P-type Ca channels are potentially regulated by PKC phosphorylation and the functional relevance of this intracellular pathway is discussed.
Fournier
F
F
Laboratoire de Neurobiologie Cellulaire, Université de Picardie, Faculté des Sciences, Amiens, France.
Charnet
P
P
Bourinet
E
E
Vilbert
C
C
Matifat
F
F
Charpentier
G
G
Navarre
P
P
Brûlé
G
G
Marlot
D
D
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D002531:Cerebellum / Q000378:metabolism*; D003001:Cloning, Molecular; D004594:Electrophysiology; D004789:Enzyme Activation; D009865:Oocytes; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D014981:Xenopus
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D012333:RNA, Messenger; D011493:Protein Kinase C