[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]--Gal-(1 --> 3)-[alpha] GalNAc-(1 --> O)-Bn

Abstract

We compared several sialyltransferase activities related to synthesis of O-linked and N-linked sialylglycoproteins 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]--Gal-(1 --> 3)--GalNAc [alpha]-(2 --> 3)-sialyltransferase activity. Sialylation of N-acetyllactosamine, lacto-N-tetraose, and benzyl [alpha]--Ga1NAc 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]--Gal-(1 --> 4)--GlcNAc mostly by [alpha]-(2 --> 3)-sialyltransferase, whereas [beta]--Gal-(1 --> 4)--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