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Calmodulin‐ and protein phosphorylation‐independent release of catecholamines from PC‐12 cells
Author(s) -
Matthies Heinrich J.G.,
Palfrey H.Clive,
Miller Richard J.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)81132-3
Subject(s) - calmodulin , secretion , protein kinase c , protein kinase a , intracellular , activator (genetics) , phosphorylation , catecholamine , chemistry , protein phosphorylation , microbiology and biotechnology , digitonin , autophosphorylation , biology , biochemistry , endocrinology , receptor , enzyme
Catecholamine secretion from PC‐12 cells can be triggered by agents that increase intracellular Ca 2+ and is enhanced by phorbol esters and agents that elevate intracellular cAMP concentrations. In mutant PC‐12 cells lacking cAMP‐dependent protein kinase (PK‐A) in which protein kinase C (PK‐C) was down‐regulated, Ca 2+ ‐dependent secretion occurred normally but was no longer enhanced by cAMP or phorbol esters. In digitonin‐permeabilized PC‐12 cells that lacked PK‐C and PK‐A, a range of calmodulin (CaM) inhibitors failed to block Ca 2+ ‐triggered catecholamine release. Moreover, Mn 2+ , a CaM activator, failed to trigger catecholamine release whereas Ba 2+ , which does not activate CaM, supported secretion. These results indicate that the basic mechanism of stimulus/secretion coupling in PC‐12 cells does not absolutely require a regulated protein phosphorylation‐ or calmodulin‐dependent step.