Chicken immunoglobulin gamma-heavy chains: limited VH gene repertoire, combinatorial diversification by D gene segments and evolution of the heavy chain locus.

摘要: cDNA clones encoding the variable and constant regions of chicken immunoglobulin (Ig) gamma-chains were obtained from spleen libraries. Southern blots kidney DNA show that region sequences eight reveal same set bands corresponding to approximately 30 cross-hybridizing VH genes one subgroup. Since randomly selected, it is likely bulk H-chains are encoded by a single Nucleotide sequence determinations two VH, D, JH region. The segments closely related each other (83% homology) as expected for or JHs 15 residues long differ amino acid. Ds markedly in (20% size (10 20 residues). These findings strongly indicate multiple (at least two) D which combinatorial joining mechanism diversify H-chains, not operative L-chain locus. most notable among Igs so-called 7S IgG because its H-chain differs many important aspects any mammalian IgG. C gamma reported here resolves this issue. 426 with four CH domains (unlike has three domains) shows 25% homology mu. epsilon length, presence distribution cysteines CH1 CH2 domains. We propose unique ancestor subclasses, discuss evolution locus presumably (mu, gamma, alpha) loci 8-10 genes.