EVIDENCE FOR THE GLYCOSYLATION OF THE GRANULOCYTE-COLONY-STIMULATING FACTOR-RECEPTOR

The granulocyte colony-stimulating factor receptor (G-CSFR) was overex pressed in WEHI-3B D+ myelomonocytic leukemia cells by the transfectio n of an expression plasmid containing the murine G-CSFR cDNA. Two diff erent forms of the G-CSFR were observed in these cells by western blot ting. Metabolic labeling and cell surface labeling demonstrated that t he majority of the G-CSFR exists in a non mature form and is presumabl y present in the cytoplasm as a 115-kDa protein. A relatively small po rtion of the G-CSFR is present as the fully mature form on the cell su rface as a 150-kDa protein; this form of the G-CSFR binds to granulocy te colony-stimulating factor (G-CSF). Both the mature and non-mature f orms of the G-CSFR appear to be N-glycosylated, as determined by glyca nase digestion and inhibition of glycosylation by tunicamycin. Glycosy lation of the G-CSFR may be of importance for the transport of the rec eptor to the cell surface. (C) 1994 Academic Press, Inc.