Nucleotide-induced inhibition of surface sialyl transferase activity on cultured Burkitt's lymphoma cells.

Sialyl transferase activity was demonstrated on the surfaces of intact, cultured lymphoblastoid cells (RAJI) derived from a Burkitt's lymphoma. Pretreatment of the cells with neuraminidase increased the labeled sialoprotein by severalfold. A nunber of nucleotides were effective in decreasing the amount of sialoprotein assembly. CMP was the most effective inhibitor. UMP, AMP, and GMP were also inhibitory, but to a lesser degree. The diphosphate derivatives were similarly inhibitory, but generally less active than their monophosphate counterparts. The cyclic nucleotides were the least effective of all nucleotides tested; cCMP and cAMP showed a small degree of activity, whereas cUMP and cGMP were without effect. These studies indicated that a number of noncyclic and cyclic nucleotides can influence the activity of the sialyl transferase system.