Figure 1. CDR-H3 plays a key role in antigen binding site diversity.
Top. The variable domains of the L and H chains are created by VJ joining, and by VDJ joining and N addition, respectively. Due to the inclusion of a D gene segment, the opportunity to introduce two sets of N nucleotide additions, and the greater flexibility in length and sequence composition, the CDR-H3 interval is the most diverse portion of the pre-immune repertoire [reviewed in (25)]. Bottom. A cartoon of the classic antigen-binding site as seen head-on. Due its central location, most bound antigens will interact with CDR-H3, including its DH component.