title: A potent dimeric peptide antagonist of interleukin-5 that binds two interleukin-5 receptor alpha chains.
abstract: Two series of peptides that specifically bind to the extracellular domain of the alpha chain of the human interleukin-5 receptor (IL-5Ralpha), but share no primary sequence homology to IL-5, were identified from libraries of random recombinant peptides. Affinity maturation procedures generated a 19-aa peptide that binds to the IL-5 receptor alpha/beta heterodimer complex with an affinity equal to that of IL-5 and is a potent and specific antagonist of IL-5 activity in a human eosinophil adhesion assay. The active form of the peptide is a disulfide-crosslinked dimer that forms spontaneously in solution. Gel filtration analysis, receptor-binding studies, and analytical ultracentrifugation reveal that the dimeric peptide binds simultaneously to two receptor alpha chains in solution. Furthermore, the dimer peptide, but not IL-5, can activate a chimeric receptor consisting of the IL-5Ralpha extracellular domain fused to the intracellular domain of the epidermal growth factor receptor, thus demonstrating that the peptide also promotes receptor dimerization in a cellular context. The functional antagonism produced by the bivalent interaction of the dimeric peptide with two IL-5R alpha chains represents a distinctive mechanism for the antagonism of cytokines that use heteromeric receptors.
authors.affiliation: Affymax Research Institute, 4001 Miranda Avenue, Palo Alto, CA 94304, USA. bruce_england@affymax.com
authors.forename: B P
authors.initials: BP
authors.lastname: England
authors.forename: P
authors.initials: P
authors.lastname: Balasubramanian
authors.forename: I
authors.initials: I
authors.lastname: Uings
authors.forename: S
authors.initials: S
authors.lastname: Bethell
authors.forename: M J
authors.initials: MJ
authors.lastname: Chen
authors.forename: P J
authors.initials: PJ
authors.lastname: Schatz
authors.forename: Q
authors.initials: Q
authors.lastname: Yin
authors.forename: Y F
authors.initials: YF
authors.lastname: Chen
authors.forename: E A
authors.initials: EA
authors.lastname: Whitehorn
authors.forename: A
authors.initials: A
authors.lastname: Tsavaler
authors.forename: C L
authors.initials: CL
authors.lastname: Martens
authors.forename: R W
authors.initials: RW
authors.lastname: Barrett
authors.forename: M
authors.initials: M
authors.lastname: McKinnon
mesh_terms: D000595:Amino Acid Sequence; D019281:Dimerization; D004804:Eosinophils / Q000187:drug effects; D006801:Humans; D015848:Interleukin-5 / Q000037:antagonists & inhibitors*; D008969:Molecular Sequence Data; D019151:Peptide Library; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology*; D018123:Receptors, Interleukin / Q000737:chemistry / Q000378:metabolism*; D053649:Receptors, Interleukin-5
chemical_list: D015848:Interleukin-5; D019151:Peptide Library; D010455:Peptides; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5