Visual AntibodyAntibody Numbering Systems
Visual Antibody supports standard antibody numbering schemes for consistent residue and CDR identification across sequences and structures. Use the Sequence Analyzer to get CDR sequences (Kabat) from your chain; use the CDR Highlighter to visualize CDR loops in 3D.
IMGT numbering
IMGT (ImMunoGeneTics) numbering is maintained by the international ImMunoGeneTics information system. It provides a unified numbering for variable (V), diversity (D), and joining (J) regions of immunoglobulins and is widely used in antibody engineering and therapeutic development. CDR boundaries are defined by IMGT (CDR1-IMGT, CDR2-IMGT, CDR3-IMGT).
Kabat numbering
Kabat numbering is a classical scheme based on sequence alignments of antibody variable regions. CDR definitions (CDR-H1, CDR-H2, CDR-H3, CDR-L1, CDR-L2, CDR-L3) follow Kabat et al. and are commonly used in structure and epitope analysis. Residue numbers can differ from IMGT due to insertions in framework regions.
Using numbering in Visual Antibody
The Sequence Analyzer and CDR Identification tools use these schemes to assign residue numbers and extract CDR sequences. Choose IMGT or Kabat in the calculator when analyzing your antibody sequence.
Sequence Analyzer →