AHo Antibody Numbering

abYsis supports all major numbering systems. The AHo numbering scheme introduced by Honegger and Plückthun is a more recent scheme for numbering residues in an antibody and can broadly be considered a more structurally correct version of the IMGT scheme:

AHo Details

In the AHo system, insertions and deletions, rather than growing from one direction, are placed symmetrically around a key position.

Another difference is that length variations in CDR-1 and CDR-2 are accounted for by a single gap position in all other schemes, whereas the Aho scheme has two locations at which gaps or insertions may be introduced.

Ultimately whilst each numbering system has advantages and disadvantages the most important aspect from the viewpoint of a research is to stick to one scheme during a particular piece of work and not inadvertently swap between different systems.