Protein phosphorylation in rat basophilic leukemia cells following stimulation for histamines release

The stimulation of the rat basophilic leukemia 2H3 (RBL-2H3) cells results in protein phosphorylation which accompanies the secretion of histamine. In the present investigations the cells were stimulated either through the IgE receptor or with the calcium ionophore A23187. Total cellular proteins were analyzed by 2-dimensional electrophoresis. The pattern of changes in 32P incorporation into polypeptides was similar following both antigen- or calcium ionophore-stimulation. At least 14 polypeptides demonstrated increased 32P incorporation following activation with either antigen or ionophore. Twelve additional phosphopolypeptides were detected in the stimulated cells which could not be seen in the absence of activation. There was one polypeptide with dephosphorylation following stimulation. Time course experiments revealed that the overall pattern of phosphorylation with both secretagogues was similar. Only 2 polypeptides were found not to be phosphorylated in the absence of extracellular Ca2+. The results indicate the phosphorylation of a complex number of polypeptides during the secretory event. It also demonstrated that the phosphorylation of most of these occur in the absence of extracellular Ca2+ and are events which precede the rise in cytoplasmic Ca2+ concentration