N-glycosylation of the human granulocyte-macrophage colony-stimulating factor receptor alpha subunit is essential for ligand binding and signal transduction.
The alpha subunit of the receptor for human granulocyte-macrophage colony-stimulating factor (GM-CSF) is a glycoprotein containing 11 potential N-glycosylation sites in the extracellular domain. We examined the role of N-glycosylation on alpha subunit membrane localization and function. Tunicamycin, an N-glycosylation inhibitor, markedly inhibited GM-CSF binding, GM-CSF-induced deoxyglucose uptake, and protein tyrosine phosphorylation in HL-60(eos) cells but did not affect cell surface expression of the alpha subunit as detected by an anti-alpha subunit monoclonal antibody. In COS cells expressing the alpha subunit and treated with tunicamycin, N-unglycosylated alpha subunit was expressed and transported to the cell surface but was not capable of binding GM-CSF. High affinity binding in COS cells expressing both alpha and beta subunits was also blocked by tunicamycin treatment. These studies indicate that N-linked oligosaccharides are essential for alpha subunit ligand binding and signaling by the human GM-CSF receptor.
Ding
D X
DX
Graduate Program in Molecular Biology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA.
Vera
J C
JC
Heaney
M L
ML
Golde
D W
DW
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D006031:Glycosylation / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D018922:HL-60 Cells; D006801:Humans; D007700:Kinetics; D008024:Ligands; D046911:Macromolecular Substances; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014162:Transfection; D014415:Tunicamycin / Q000494:pharmacology
D008024:Ligands; D046911:Macromolecular Substances; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D014415:Tunicamycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor