Mono-ADP-Ribosylation in Brain: Purification and Characterization of ADP-Ribosyltransferases Affecting Actin from Rat Brain

Four ADP-ribosyltransferases that acted on non-muscle actin were purified more than 3,000-fold from rat brain extract. The molecular weights of these brain ADP-ribosyltransferases were 66,000 as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration on TSK gel G3000SW. The Km values for NAD were approximately 20 microM. These enzymes were not inhibited by thymidine or nicotinamide, but were inhibited by ADP and ADP-ribose. Two soluble ADP-ribosylation factors purified from rat brain had different effects on the four ADP-ribosyltransferases during the ADP-ribosylation of non-muscle actin. These ADP-ribosyltransferases modified not only actin but also the stimulatory guanine nucleotide-binding protein of adenylate cyclase, Gs, and another guanine nucleotide-binding protein in brain, Go. These findings suggest that the four brain ADP-ribosyltransferases are concerned with nerve functions in the central nervous system.