Alpha-(2-->3)- and alpha-(2-->6)-sialyltransferase activities present in three variants of Ehrlich tumor cells: identification of the products derived from N-acetyllactosamine and beta-D-Gal-(1-->3)-alpha-D-GalNAc-(1-->O)-Bn.

We compared several sialytransferase activities related to synthesis of O-linked and N-linked sialyglycoproteins in Ehrlich ascites tumor cells that grow normally in murine ascites, but are not adherent nor grow in tissue culture (na-EAT cells), with those in cells that were selected to grow in tissue culture and adhere to extracellular matrices (a-EAT cells). Crude Golgi preparations from both cell types contained predominantly beta-D-Gal-(1-->3)-D-GalNAc alpha-(2-->3)-sialyltransferase activity. Sialylation of N-acetyllactosamine, lacto-N-tetraose, and benzyl alpha-D-GalNAc occurred at from 1 to 4% of that activity. Analysis, by ion-exchange HPLC at high pH, of sialylated N-acetyllactosamine showed that na-EAT cells sialylated beta-D-Gal-(1-->4)-D-GlcNAc mostly by alpha-(2-->3)-sialyltransferase, whereas beta-D-Gal-(1-->4)-D-GlcNAc alpha-(2-->6)-sialyltransferase activity was prominent in a-EAT cells. In addition, preparations from na-EAT cells formed significant quantities of an unknown tritiated product from CMP-[9-3H]sialic acid, suggesting at least one other difference in enzyme levels between the cell types. a-EAT cells reestablished in murine ascites for 11 passages retained the sialyltransferase levels characteristic of a-EAT cells. When viable cells were labeled with D-[3H]glucosamine, na-EAT cells formed larger amounts of sialic acid in O-linked glycoproteins than did a-EAT cells.