Premium
Phorbol Myristate Acetate Induces the Phosphorylation of Plasma Membrane‐Associated Proteins in Sea Urchin Eggs
Author(s) -
CHANDLER DOUGLAS E.,
VACQUIER VICTOR D.
Publication year - 1988
Publication title -
development, growth and differentiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.864
H-Index - 66
eISSN - 1440-169X
pISSN - 0012-1592
DOI - 10.1111/j.1440-169x.1988.00049.x
Subject(s) - phosphorylation , protein kinase c , sea urchin , phorbol , antiporter , diacylglycerol kinase , microbiology and biotechnology , protein kinase a , biochemistry , protein phosphorylation , serine , biology , strongylocentrotus purpuratus , kinase , chemistry , membrane
Immediately after fertilization sea urchin eggs undergo an increase in cytoplasmic pH from 6.8 to 7.2. This pH change occurs by activation of a Na + /H + antiporter, and is a necessary signal for later steps in metabolic activation of development. Activators of protein kinase C such as phorbol myristate acetate (PMA) and diacylglycerol produce a similar pH increase in eggs. Phosphorylation of the antiporter or a regulatory protein may be a step in activating Na + /H + exchange. Here we show that treatment of sea urchin eggs ( S. purpuratus ) with PMA results in increased phosphorylation of over a dozen proteins. Of these, three proteins of Mr=240, 92 and 80 kD are located in the egg cortex; under‐representation of these bands in isolated cortical granules suggests that they are plasma membrane‐associated. Phosphorylation of the 92 kD band is concentration‐dependent over a range of 10 to 1000 nM PMA and occurs over a time‐course of 1 to 3 min. Phosphoamino acid analysis indicates that phosphorylation is on serine residues. Phosphorylation appeares to be mediated by protein kinase C since the inactive PMA analogue, 4α‐phorbol 12, 13‐didecanoate, does not induce phosphorylation nor does experimental alkalinization of the egg cytoplasm.