Secretion from rat basophilic RBL-2H3 cells is associated with diphosphorylation of myosin light chains by myosin light chain kinase as well as phosphorylation by protein kinase C.

摘要: The phosphorylation of myosin light chains and heavy by protein kinase C is known to be temporally correlated with Ca(2+)-dependent secretion granules from RBL-2H3 cells (Ludowyke, R. I., Peleg, Beaven, M. A., Adelstein, S. (1989) J. Biol. Chem. 264, 12492-12501). We now report that whereas are predominantly monophosphorylated the Ca2+/calmodulin-dependent chain at serine 19 in unstimulated cells, stimulation antigen or other stimulants causes additional threonine 18, as well 1 2. This diphosphorylation 18 monophosphorylation rate extent degranulation. Secretion occurs whenever both enzymes stimulated combination low concentrations A23187 (50 nM) phorbol 12-myristate 13-acetate (20 nM). These phosphorylations appear closely associated exocytosis cells. Thus, phosphorylation, secretion, can blocked inhibitors KT5926 ML-7. More specifically, ester alone induces exclusively, but fails induce until accompanied A23187, which activates kinase. Conversely, selective suppression (with Ro31-7549 antigen-stimulated cells) suppresses degranulation, thereby indicating a requirement for C.