Comparison of C(H)1 domains in different classes of murine antibodies

The C(H)1 domains of antibodies belonging to the following five murine immunoglobulin (Ig) classes IgG1, IgG2a, IgG2b, IgG3 and IgA have been compared. The IgG C(H)1 domain structures are, as would be expected, similar overall, but show local conformational variations. When compared with IgG C(H)1 domain structures, the IgA C(H)1 domain displays several significant structural differences, which are a consequence of insertions/deletions and specific structural constraints. In regions of structural differences in the IgG C(H)1 domains, the spatial correspondence of residues is not reflected by conventional (Kabat) sequence number. Thus the sequence alignment and numbering for C(H)1 domains has been revised to be consistent with the three-dimensional alignments. (C) 1996 Academic Press Limited