title: Involvement of the fourth alpha-helix of mouse granulocyte-macrophage colony-stimulating factor in binding to the alpha-subunit of the receptor complex.
abstract: Mouse granulocyte-macrophage colony-stimulating factor (mGM-CSF) proteins with substitutions for residues located within alpha-helix D were examined for biological activity and receptor binding properties. Alanine substitutions of the surface exposed positions indicated that several residues contribute to the ligand-receptor interface. Position K108 and particularly D102 appeared to dominate the binding epitope recognized by mGM-R alpha. Several amino acid substitutions were made for K108 which reduced binding with concommitant losses in bioactivity. Substitutions for D102 resulted in binding affinities less than 0.1% that of the wild-type mGM-CSF and bioactivity decreased to 1.0%. Comparative analysis using high and low affinity binding conditions indicated that mGM-R beta binding was unaffected by these mutations.
authors.affiliation: Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304-1104, USA.
authors.forename: S W
authors.initials: SW
authors.lastname: Altmann
authors.forename: N
authors.initials: N
authors.lastname: Patel
authors.forename: R A
authors.initials: RA
authors.lastname: Kastelein
mesh_terms: D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001667:Binding, Competitive; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry* / Q000378:metabolism*; D011994:Recombinant Proteins; D017421:Sequence Analysis
chemical_list: D000596:Amino Acids; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor