Intrinsic ADP-ribose transferase activity versus levels of mono(adp-ribose)protein conjugates in proliferating Ehrlich ascites tumor cells.

Transition of proliferating Ehrlich ascites tumor cells (3 days after transplantation) to the non-proliferating status (8--14 days after transplantation) was associated with an increase in total mono (ADP-ribose) protein conjugates. This increase was largely confined to the NH2OH-resistant subfraction. When the amounts of mono-(ADP-ribose) conjugates from 20% trichloroacetic acid precipitates were compared with those from 5% perchloric acid precipitates, no significant differences were seen. This fact excludes histone H1 as a major mono (ADP-ribose) acceptor in vivo in these cells. Transition to the resting state was also associated with a small decrease in NAD levels, and with no significant changes of total ADP-ribose transferase activity. However intrinsic ADP-ribose transferase activity as expressed in permeabilized cells was increased, being correlated with the changes in the level of the NH2OH-resistant mono (ADP-ribose) protein conjugates. This shows that alterations in intrinsic transferase activity may, in general, indicate similar alterations in major subfractions of ADP-ribose conjugates. Intrinsic ADP-ribose transferase activity exhibited an inverse relationship to ornithine decarboxylase activity.