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Phosphorylation and dephosphorylation of soluble proteins in human eosinophils
Author(s) -
Ramesh Kashi S.,
Rocklin Ross E.,
Pincus Stephanie H.
Publication year - 1987
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240340306
Subject(s) - phosphorylation , dephosphorylation , protein phosphorylation , chemistry , biochemistry , sodium dodecyl sulfate , activator (genetics) , phosphatase , protein kinase a , gene
The effect of phorbol 12‐myristate 13‐acetate (PMA), calcium ionophore (A23187), opsonized zymosan (OZ), and N‐formylmethionyl‐leucyl‐phenylalanine (f‐Met‐Leu‐Phe) on protein phosphorylation was examined in purified eosinophils (eos) isolated from human peripheral blood. Eos were prelabeled with [ 32 P]orthophosphate, stimulated with several activating agents for varying periods of time. The soluble proteins were then analyzed by one‐dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and autoradiography. In resting eos, there was phosphorylation of endogenous soluble proteins with molecular weights of 12, 16, 21, 40, and 66 kilodaltons (kDa). PMA, a potent activator of oxidative metabolism, induced phosphorylation of 19‐, 40‐, and 67‐kDa proteins. A23187, a strong degranulating stimulus, caused phosphorylation of 40‐, 53‐, and 67‐kDa proteins. OZ, a relatively weak stimulus for eos function, caused phosphorylation of 30–34‐, 59‐, 67‐, and 93‐kDa proteins. In addition, all the above stimuli caused a time‐dependent dephosphorylation of 21‐kDa protein. In contrast, f‐Met‐Leu‐Phe caused neither phosphorylatiop of new proteins nor dephosphorylation of preexisting eos proteins. These findings demonstrate that selected stimuli affect phosphorylation of soluble eos protein. These results also suggest that phosphorylation of specific proteins in eos is an intermediary step in external stimulus‐induced cell activation, which may involve many different cell functions.