L chain peptide maps of rabbit IgG of different allotypes

Light (L) chains of IgG from rabbits homozygous and heterozygous for allotypic specificities (As4, 5 and 6) at the b locus were examined by the technique of peptide mapping. They have between twenty-six and thirty dark peptides, 40 per cent of them being common to all three allotypic specificities. About 60 per cent peptides are shared by any two specificities (As4—5, As4—6 and As5—6). Amongst the peptides unique for each specificity there was always one most prominent peptide present by which the specificity could be identified by peptide maps. The L chains from IgG of heterozygous rabbits have in general all the peptides characteristic of both specificities of the homozygous animal, although As4 peptides are always most prominent. Thus multiple peptide differences between L chains of three allotypic specificities were found.