Evidence for the presence of protein kinase C in barnacle muscle fibers.
1. The efflux of 22Na from single barnacle muscle fibers poisoned with ouabain (strophanthin G) is found to be very sensitive to the tumor-promoting agent, phorbol dibutyrate (PDBu). 2. Injection or external application of PDBu leads to stimulation of the ouabain-insensitive component of the Na efflux. This response is dose-dependent, the minimal effective concentration being about 10(-8)M. 3. The observed stimulatory response is completely dependent on the presence of external Ca2+. 4. Biochemical studies including immunoblot analysis reveal the presence in barnacle muscle of a protein kinase C with a mol. wt of 80,000, the activity of which is dependent on phosphatidylserine and Ca2+. 5. Taken together, these results support the view that barnacle muscle fibers possess protein kinase C. They also raise the possibility that protein kinase C plays a role in modulating the ouabain-insensitive component of the Na efflux.
D000818:Animals; D002118:Calcium / Q000494:pharmacology; D009132:Muscles / Q000187:drug effects / Q000201:enzymology; D010042:Ouabain / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D001468:Thoracica / Q000201:enzymology*
D010703:Phorbol Esters; D015240:Phorbol 12,13-Dibutyrate; D010042:Ouabain; D012964:Sodium; D011493:Protein Kinase C; D002118:Calcium