CHARACTERIZATION OF IN-VIVO PHOSPHORYLATION OF ACTIVIN TYPE-II RECEPTOR

An antiserum was generated against a C-terminal peptide of the mouse activin type II receptor (ActR-II), which specifically immunoprecipitates ActR-II protein transiently expressed in COS-1 cells. Autophosphorylation activity of the ActR-II was examined in [32P]orthophosphate labeled COS-1 cells. The immunoprecipitated ActR-II protein was found to be phosphorylated on serine residues in the absence of ligand stimulation, and the phosphorylation was slightly increased after stimulation with activin A. © 1993 Academic Press, Inc.