Structural Basis of the A14 and A15 Allotypic Specificities in Rabbit Immunoglobulin G

The structural basis for the A14 and A15 allotypic specificities of rabbit immunoglobulin G was investigated with Fe fragments prepared from homozygous rabbits. The presence of threonine in the Cγ2 region (position 309: Eu numbering) correlates with the A14 allotype; the presence of alanine at this same position correlates with the A15. Now that the sequence of the Cγ2 region of rabbit IgG has been completely elucidated, a high degree of homology of the constant region domains of rabbit and human γ chains is apparent (about 60-80%).