Molecular cloning of rabbit γ heavy chain mRNA

A cDNA library of rabbit spleen mRNA was screened for immunoglobulin heavy chain sequences. In this paper we report the nucleotide sequence of two cDNA clones containing part of the constant region of the rabbit γ heavy chain mRNA. The sequence encodes part of the CH2 domain (amino acids 268 to 340), the entire CH3 domain (amino acids 341 to 447) and the 3′ untranslated region. This nucleotide sequence has been compared to the corresponding sequences of mouse γ1, γ2a and γ2b genes. The homologies between rabbit γ chain gene sequence and each of the mouse γ chain gene sequences are of the same magnitude order. This comparison shows that the CH2 domains are more homologous to each other than CH3 domains or 3′ untranslated sequences. The presence of species specific nucleotide positions suggests that mouse γ chain genes could have evolved from a common ancestor shortly after mouse-rabbit species separation. Genomic blot analysis of rabbit liver DNA with the rabbit Cγ probes shows a limited number of related sequences, with little restriction site polymorphism between individual rabbits.