IMGT®, the international ImMunoGeneTics information system®

Complementarity Determining Regions (CDR-IMGT)

The Complementarity Determining Regions (CDR) and the Framework Regions (FR) are parts of the variable regions of the Immunoglobulin and T cell Receptor chains. The IMGT unique numbering for V-REGION [1] has allowed to redefine the limits of the Complementarity Determining Regions and Framework Regions, designated as CDR-IMGT and FR-IMGT, respectively in IMGT. The IMGT unique numbering for V-DOMAIN provides a standardized numbering for the CDR3-IMGT and FR4-IMGT of rearranged V-J-REGION and V-D-J-REGION (IMGT Scientific chart).

The lengths of the FR-IMGT and CDR-IMGT are in themselves crucial information which characterize variable regions belonging to a group, a subgroup and/or a gene [2-5]. Tables of the FR-IMGT and CDR-IMGT lengths are available in the IMGT Repertoire.

Amino acids (and codons) belonging to CDR-IMGT of same length and  located at the same position in different sequences can be compared without requiring sequence alignments.

Correspondence between V numberings, and more particularly Correspondence between numberings for the CDR-IMGT lengths (horizontal display) (IMGT Scientific chart) allows to compare CDR-IMGT with previous data.