Three conserved motifs in the extracellular domain of the human granulocyte-macrophage colony-stimulating factor receptor subunit are essential for ligand binding and surface expression.
The receptor for the human granulocyte-macrophage colony-stimulating factor (GM-CSF) (GM-R) is a heterodimeric complex consisting of two subunits, GM-R alpha and GM-R beta. Structural analyses have shown a number of highly conserved amino acid motifs present in both GM-R alpha and GM-R beta. These motifs include QYFLY, CXW, XW, and WSXWS motifs in the extracellular domain; a conserved cysteine in the transmembrane domain; and the entire cytoplasmic domain, including the LXVLX box in the carboxy terminal region of the cytoplasmic domain. We have investigated the role of these motifs in GM-R alpha by examining the effects of specific motif mutations on ligand binding and surface expression. Transient expression of these mutant GM-R alpha subunits in COS cells shows that these extracellular motis are essential for ligand binding. Alterations of the cytoplasmic region of GM-R alpha do not alter GM-CSF binding or the reconstitution of high-affinity receptors when coexpressed with GM-R beta. Permeabilization and immunostaining of cells transfected with mutant GM-R alpha subunits yields data suggesting that each of the mutant subunits is present in the cytoplasm. Immunostaining of both intact and permeabilized COS cells transiently transfected with wild-type or mutant GM-R alpha s showed that extracellular domain mutants accumulated in the cytoplasm and were not efficiently transported to the cell surface.
Doshi
P D
PD
Department of Hematology, University of Rochester, NY.
DiPersio
J F
JF
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002461:Cell Line, Transformed; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D017124:Conserved Sequence; D015870:Gene Expression; D006801:Humans; D007668:Kidney; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection
D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor