Fig. 2. The heavy chains of bovine antibodies can encode a very long CDR H3, which contrasts with the equivalent CDRs of human, mouse and heavy chain camelid antibodies.

Structures of antigen-binding fragment regions from bovine (BLV1H12, Protein Data Bank (PDB) ID 4K3D⁵⁸; part a), human (PG9, PDB ID 3U2S⁸⁶; part b), mouse (93F3, PDB ID 1T4K⁸⁷; part c) and camelid (VHH-5, PDB ID 5U65 (ref.⁸⁸); part d) antibodies (shown in cartoon representation). Heavy chains are coloured blue and light chains are coloured green. Heavy chain complementarity-determining region 3 (CDR H3; or CDR3 in the case of the camelid antibody) for each structure is coloured orange. PG9 contains a relatively long CDR H3 for human antibodies. Structures were rendered with PyMOL (version 1.8.6.0; Schrödinger LLC).