The immunoglobulin heavy chain locus in the reptile Anolis carolinensis

We describe the entire immunoglobulin heavy chain (IgH) locus from the reptile Anolis carolinensis. The heavy chain constant (CH) region includes Cμ, Cδ and Cυ genes. This is the first description of a Cυ gene in the reptilian class. Variable (VH), diversity (DH) and joining (JH) genes are located 5′ from the constant (CH) chain complex locus. The Cμ and Cυ genes encode antibodies with four immunoglobulin domains. The Cδ gene encoded an 11 domain delta heavy chain as in Eublepharis macularius. Seventy VH genes, belonging to 28 families, were identified, and they can be sorted into five broader groups. The similarity of the organization of the reptilian genes with those of amphibians and mammals suggests the existence of a process of heavy chain genomic reorganization before the radiation of tetrapod vertebrates.