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. 1999 Feb 15;189(4):747–752. doi: 10.1084/jem.189.4.747

Figure 3.

Figure 3

Comparison of IgG1 and IgA1 CH3 sequences and IgG1 structure in the area homologous to several phage-derived peptides. (a) The A12 peptide alignment with human IgA1 and IgG1. IgGSTR indicates structural features of IgG1 where < denotes a β-strand running in a descending orientation (i.e., hinge to CH3 direction), > denotes a β-strand running in an ascending direction (i.e., CH3 to hinge direction), and – denotes a loop or open structure (29). (b) Comparison of several mammalian IgA sequences with the four human IgG subclasses showing the additional IgA-specific amino acids present in the loop at positions 402–410 in the IgA sequence. hu, human; gr, gorilla; mur, murine; rab, rabbit. (c) IgA1 Cα3 mutants L1, L2, and L3 aligned with the Cα3 and Cγ3 wild-type sequences and Cγ3 structure (IgGSTR). = denotes sequence identity in the mutants, – denotes a space introduced in the IgG sequence to maximize homology, and IgGSTR is labeled according to panel a. Numbering of IgA1 and IgG1 is according to references 5 and 29, respectively.