Purification and identification of ADP-ribosylated proteins from bull testis intact nuclei

Isolated, intact bull testis nuclei were incubated with [14C] NAD. A large amount of radioactivity was associated to loosely bound chromosomal proteins extracted with 0.35M NaCl and fractionated with trichloroacetic acid. The labelled nuclear proteins included essentially a number of components belonging to the low mobility group. Mg2(+)-catalyzed alkali digestion of radioactive proteins and further analysis demonstrated that the final products were 5'-AMP and phospho-ribosyl-AMP, which arise from the hydrolysis of poly(ADP-ribose).