Biochemical identification of glycosylation inhibiting factor.

Rat monoclonal antibody against mouse glycosylation inhibiting factors was obtained, and radiolabeled glycosylation inhibiting factors from the mouse T-cell hybridoma, 231F1 cells, were purified by using the monoclonal antibody and antilipomodulin antibody. Analysis of the affinity-purified lymphokine by PAGE demonstrated two proteins of 14.4 kDa and 41 kDa. Both proteins migrated similarly under the reduced and unreduced conditions, indicating that each of the two species consist of a single polypeptide chain. Biologic activity of the lymphokine was recovered by extraction of the proteins from gel slices followed by renaturation. Evidence was obtained that suggested the 14.4-kDa peptide was a degradation product of the 41-kDa molecules. The 14.4-kDa peptide was also recovered by extraction of the surface-labeled 231F1 cells with Ca2+ chelator, indicating that the glycosylation inhibiting factor is associated with the cell surface.