Response of cell surface glycosyl transferases to dibutyryl adenosine-3',5' cyclic monophosphate in virus-transformed and normal cells.

Galactosyl and sialyl transferases in the plasma membrane of SV40-transformed mouse cells were inhibited by 0.5 mM dibutyryl adenosine-3′,5′ cyclic monophosphate (db-cAMP) while those of normal cells did not respond to this compound. The differential effects of dibutyryl adenosine-3′,5′ cyclic monophosphate on the membrane-bound glycosyl transferases were observed both in isolated plasma membrane and in intact cell membrane. It is suggested that some of the morphological restorations of normal cell characteristics during reverse transformation are partly due to the direct effect of this compound on the cell membrane.