Evidence for the glycosylation of the granulocyte colony-stimulating factor receptor.

The granulocyte colony-stimulating factor receptor (G-CSFR) was overexpressed in WEHI-3B D+ myelomonocytic leukemia cells by the transfection of an expression plasmid containing the murine G-CSFR cDNA. Two different forms of the G-CSFR were observed in these cells by western blotting. Metabolic labeling and cell surface labeling demonstrated that the majority of the G-CSFR exists in a non-mature form and is presumably present in the cytoplasm as a 115-kDa protein. A relatively small portion of the G-CSFR is present as the fully mature form on the cell surface as a 150-kDa protein; this form of the G-CSFR binds to granulocyte colony-stimulating factor (G-CSF). Both the mature and non-mature forms of the G-CSFR appear to be N-glycosylated, as determined by glycanase digestion and inhibition of glycosylation by tunicamycin. Glycosylation of the G-CSFR may be of importance for the transport of the receptor to the cell surface.