scholarly journals N-Glycosylation of the Human Granulocyte-Macrophage Colony-stimulating Factor Receptor α Subunit Is Essential for Ligand Binding and Signal Transduction

1995 ◽  
Vol 270 (41) ◽  
pp. 24580-24584 ◽  
Author(s):  
Dawn Xiao-Hong Ding ◽  
Juan Carlos Vera ◽  
Mark L. Heaney ◽  
David W. Golde
Blood ◽  
1994 ◽  
Vol 84 (8) ◽  
pp. 2539-2553 ◽  
Author(s):  
PD Doshi ◽  
JF DiPersio

Abstract 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.


Blood ◽  
1994 ◽  
Vol 84 (8) ◽  
pp. 2539-2553 ◽  
Author(s):  
PD Doshi ◽  
JF DiPersio

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.


Blood ◽  
1992 ◽  
Vol 79 (12) ◽  
pp. 3350-3354 ◽  
Author(s):  
MA Raines ◽  
DW Golde ◽  
M Daeipour ◽  
AE Nel

Receptors of the hematopoietin superfamily, including the granulocyte- macrophage colony-stimulating factor (GM-CSF) receptor, lack a tyrosine kinase domain as well as other sequences indicative of a known signaling mechanism. In this report, we identify the serine/threonine kinase, microtubule-associated protein 2 (MAP2) kinase, as an intermediate in the GM-CSF signal transduction pathway. Treatment of peripheral blood neutrophils or terminally differentiated HL-60 cells with GM-CSF induced a rapid and dose-dependent increase in MAP2 kinase activity. Maximal activity occurred within 5 minutes and the kinetics of the response varied depending on the target cell (prolonged in neutrophils and transient in neutrophilic HL-60 cells). MAP2 kinase activity in these cells correlates with the induction of a 42-Kd tyrosine phosphoprotein. Furthermore, tyrosine phosphorylation is necessary for MAP2 kinase activation since its activity is inhibited by treatment with the tyrosine kinase inhibitor, erbstatin analog. These data suggest that tyrosine phosphorylation is important in GM-CSF- mediated signal transduction and that MAP2 kinase activation may be a central biochemical event involved in its signaling.


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