MOLECULAR CLONING OF THE GUINEA-PIG IL-5 RECEPTOR α AND β SUBUNITS AND RECONSTITUTION OF A HIGH AFFINITY RECEPTOR

• Published in: Cytokine (Philadelphia, Pa.) Vol. 12; no. 7; pp. 858 - 866
• Main Authors: Scott, Clay W, Logsdon, Naomi J., Wilkins, Deidre E., Norris, Tyrrell E., Sobotka-Briner, Cindy, Hubbs, Stephen, Graham, Alexander
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2000
• Subjects: Amino Acid Sequence; Animals; Cell Line; Cloning, Molecular; cytokine/eosinophil/guinea-pig/interleukin 5/IL-5R; Gene Expression; Guinea Pigs; Humans; Interleukin-5 - metabolism; Molecular Sequence Data; Protein Binding; Protein Isoforms - genetics; Protein Isoforms - metabolism; Receptors, Interleukin - genetics; Receptors, Interleukin - metabolism; Receptors, Interleukin-5; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Analysis, DNA; Spodoptera - cytology; cytokine/eosinophil/guinea-pig/interleukin 5/IL-5R
• ISSN: 1043-4666; 1096-0023
• DOI: 10.1006/cyto.1999.0657

The functional IL-5 receptor is a heteromeric complex consisting of an α and β subunit. The cloning, sequencing and expression of guinea-pig IL-5Rα and β subunits is described. The guinea-pig IL-5Rα subunit cDNA encodes a protein of Mr47kDa, which is 72 and 66% homologous to the human and murine orthologs, respectively. Three guinea-pig IL-5Rβ subunit cDNA clones were isolated, which differ in the N-terminus and are 56–64% homologous to the human and murine IL-5Rβ subunits. Expressing human IL-5Rαβ and guinea-pig IL-5Rαβ1in the baculovirus-insect cell system resulted in recombinant receptors which bound hIL-5 with high affinity (Kd=0.19 and 0.11nM, respectively). Expressing just gpIL-5Rα was not sufficient to demonstrate binding. This contrasts with the human receptor, where hIL-5Rα alone can bind hIL-5 with high affinity. gpIL-5Rαβ1bound both hIL-5 and mIL-5 with comparable affinity (Ki=0.10 and 0.06nM), similar to that seen with hIL-5Rαβ. Thus, both the heteromeric hIL-5R and gpIL-5Rαβ1can bind multiple IL-5 orthologs with high affinity whereas the murine IL-5R is selective for the murine ligand.