Effects of phosphatase inhibitors and a protein phosphatase on norepinephrine secretion by permeabilized bovine chromaffin cells.
Biochim Biophys Acta
; 1092(3): 384-90, 1991 May 17.
Article
em En
| MEDLINE
| ID: mdl-1646643
ABSTRACT
A protein phosphatase and phosphatase inhibitors were used to examine the role of protein phosphorylation in the regulation of norepinephrine secretion in digitonin-permeabilized bovine chromaffin cells. Addition of okadaic acid, a potent inhibitor of type 1 and type 2A protein phosphatases, or 1-naphthylphosphate, a more general phosphatase inhibitor, to digitonin-permeabilized chromaffin cells caused about a 100% increase in the amount of norepinephrine secreted in the absence of Ca2+ (in 5 mM EGTA) without affecting the amount of norepinephrine secreted in the presence of 10 microM free Ca2+. This stimulation of norepinephrine secretion by protein phosphatase inhibitors suggests that in the absence of Ca2+ there is a slow rate phosphorylation and that this phosphorylation triggers secretion. Addition of an exogenous type 2A protein phosphatase caused almost a 50% decrease in Ca(2+)-dependent norepinephrine secretion. Thus, the amounts of norepinephrine released both in the absence of Ca2+ and in the presence of Ca2+ appear to depend upon the level of protein phosphorylation.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas
/
Norepinefrina
/
Medula Suprarrenal
/
Fosfoproteínas Fosfatases
Limite:
Animals
Idioma:
En
Revista:
Biochim Biophys Acta
Ano de publicação:
1991
Tipo de documento:
Article