ELONGATION IN A DICTYOSTELIUM IN-VITRO TRANSLATION SYSTEM IS AFFECTEDBY CALMODULIN ANTAGONISTS

We have previously shown that the Dictyostelium discoideum ribosomal p rotein L19 specifically binds Ca2+/calmodulin [Sonneman et al. (1991) J. Biol. Chem. 266, 23091-23096]. To investigate the role of calmoduli n in the regulation of protein synthesis, we have now established an i n vitro protein synthesizing system from Dictyostelium cells which can elongate polypeptide chains with high efficiency. Various calmodulin antagonists affected translation in this system. The inhibitory effect s of the antagonists could be partially reversed by addition of calmod ulin. A monoclonal antibody against D. discoideum calmodulin also spec ifically inhibited protein synthesis. Similar effects of calmodulin an tagonists were found in a standard wheat germ in vitro translation sys tem.