The Chicken Leukocyte Receptor Complex Encodes a Family of Different Affinity FcY Receptors

摘要: Chicken Ig-like receptors (CHIR) form a large family in the leukocyte receptor complex on microchromosome 31 with inhibitory, activating, and bifunctional receptors. Recently, we characterized CHIR-AB1 as high-affinity, primordial FcY receptor. Given that CHIR represents multigene family, it is plausible more than single binds to IgY. Therefore, after comparing CHIR-AB1-like sequences databases, cloned homologues from two individual chickens representing lines M11 R11 primers binding highly conserved regions. In both this approach yielded 18 different CHIR-AB amino acid versions, one sequence out of each line was identical previously B19 Ig domain additional R11-M11 pairs. All M11-derived were then expressed soluble human fusion proteins. Following standardization protein concentration an ELISA, IgY, IgM, IgA activities determined by ELISA. Six proteins recognized whereas none bound IgM IgA. The affinities selected using surface plasmon resonance yielding equilibrium constant between 25 nM for high binders 260 low binders. Sequence comparisons subsequent mutational analysis residues identified five acids are potentially involved IgY binding. These results imply multiple variable affinity encoded locus chicken may express unique well