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Phosphorylation by Protein Kinase C of Annexin 2 in Chromaffin Cells Stimulated by Nicotine
Author(s) -
Delouche Bruno,
Pradel LouiseAnne,
Henry JeanPierre
Publication year - 1997
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1997.68041720.x
Subject(s) - phosphorylation , protein kinase a , protein kinase c , chromaffin cell , protein phosphorylation , kinase , microbiology and biotechnology , okadaic acid , biochemistry , staurosporine , chemistry , annexin , phosphatase , biology , endocrinology , adrenal medulla , catecholamine , in vitro
Annexin 2 phosphorylated in vitro by protein kinase C has been shown to restore partially catecholamine secretion in streptolysin O‐permeabilized chromaffin cells depleted of their protein kinase C activity. This result suggested a phosphorylation of annexin 2 in stimulated cells. Nicotine stimulation induced an increase of 32 P incorporation in annexin 2 heavy chain concomitant with catecholamine release. This incorporation results from phosphorylation by protein kinase C because (a) serine was the only phosphorylated residue, (b) 32 P incorporation was inhibited by the protein kinase inhibitors H7, GF 109203X, and staurosporine, and (c) activators of this enzyme, 12‐ O ‐tetradecanoylphorbol 13‐acetate and 1,2‐dioctanoylglycerate, increased the incorporation of radioactivity. The phosphorylated heavy chain had an electrophoretic mobility lower than that of the unmodified one, thus allowing determination of the fraction of phosphorylated protein. In the resting state, a significant fraction of annexin 2 heavy chain was phosphorylated, and nicotine stimulation resulted in an activation of both phosphorylation and dephosphorylation. Phosphorylation was largely increased in the presence of okadaic acid, indicating the involvement of type 1 and 2A phosphatases.