Phosphorylation of elongation factor 2 during Ca(2+)-mediated secretion from rat parotid acini.
In this paper we report the rapid phosphorylation of a cytosolic 100 kDa protein during stimulation of secretion from dispersed aggregates of parotid acinar cells with Ca(2+)-mobilizing secretagogues (carbachol, Substance P, ATP and the Ca2+ ionophore A23187). Phosphorylation was inhibited by removal of extracellular Ca2+ but was not observed during stimulation with phorbol esters, suggesting that this protein is not a substrate for protein kinase C. Two-dimensional PAGE and immunoprecipitation with a specific antiserum indicated that this protein is elongation factor 2, whose Ca2+ calmodulin-dependent phosphorylation has been shown to inhibit protein synthesis [Nairn & Palfrey (1987) J. Biol. Chem. 262, 17299-17303]. These results suggest that phosphorylation of elongation factor 2 is the molecular mechanism for the inhibition of protein synthesis which has been previously observed in rat parotid cells during stimulation with Ca(2+)-mobilizing secretagogues.
Department of Anatomy, University of Ottawa, Ontario, Canada.
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Hincke
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Nairn
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D001345:Autoradiography; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D010306:Parotid Gland / Q000187:drug effects / Q000378:metabolism*; D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D013268:Stimulation, Chemical; D013373:Substance P / Q000494:pharmacology
D020652:Peptide Elongation Factor 2; D010445:Peptide Elongation Factors; D013373:Substance P; D000001:Calcimycin; D000255:Adenosine Triphosphate; D002217:Carbachol; D002118:Calcium