Separate functions for the two modules of the membrane-proximal cytokine binding domain of glycoprotein 190, the leukemia inhibitory factor low affinity receptor, in ligand binding and receptor activation.
The receptor for the cytokine leukemia inhibitory factor (LIF) associates the low affinity binding component gp190 and the high affinity converter gp130. Both are members of the hematopoietic receptors family characterized by the cytokine receptor homology (CRH) domain, which consists of two barrel-like modules of around 100 amino acids each. The gp190 is among the very few members of this large family to contain two CRH domains. The membrane-distal one (herein called D1) is followed by an immunoglobulin-like domain, a membrane-proximal CRH domain called D2, and three type III fibronectin-like repeats. A minimal D1IgD2 fragment is required for binding LIF. By using transmembrane forms of deletion mutants in gp190 ectodomain, we demonstrated that removal of D1 led to spontaneous activation of the receptor and that this property was devoted to a peptidic sequence localized within the last 42 amino acids of the carboxyl-terminal module of D2. By using soluble forms of deletion mutants made by progressive truncations from the end of the D1IgD2 fragment, we demonstrated that the carboxyl-terminal module of D2 was dispensable for LIF binding and that the correct conformation of the D1Ig fragment required a full amino-terminal module of D2. Therefore, the two constitutive modules of the membrane-proximal CRH domain D2 of gp190 fulfill two distinct roles in gp190 function, i.e. in stabilizing the conformation of gp190 allowing LIF binding and in activating the receptor.
Voisin
Mathieu-Benoit
MB
CNRS UMR 5540, Université de Bordeaux II, 146 Rue Léo Saignat, 33076 Bordeaux, France.
Bitard
Juliette
J
Daburon
Sophie
S
Moreau
Jean-François
JF
Taupin
Jean-Luc
JL
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D000951:Antigens, Neoplasm / Q000737:chemistry* / Q000378:metabolism*; D016466:CHO Cells; D019556:COS Cells; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D016207:Cytokines / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005353:Fibronectins / Q000378:metabolism; D005434:Flow Cytometry; D017353:Gene Deletion; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; D008024:Ligands; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D018121:Receptors, Cytokine / Q000737:chemistry* / Q000378:metabolism; D053606:Receptors, OSM-LIF; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D016207:Cytokines; D004268:DNA-Binding Proteins; D005353:Fibronectins; D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; C507840:LIFR protein, human; D053605:Leukemia Inhibitory Factor; D053680:Leukemia Inhibitory Factor Receptor alpha Subunit; C507838:Lif protein, mouse; C507841:Lifr protein, mouse; D008024:Ligands; D008222:Lymphokines; D018121:Receptors, Cytokine; D053606:Receptors, OSM-LIF; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; C494087:Stat3 protein, mouse; D015534:Trans-Activators; C031192:oncofetal antigens