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Definition of the FR-IMGT and CDR-IMGT regions

Reference: Lefranc, M.-P., The Immunologist, 7, 132-136 (1999).

The definition of the FR-IMGT and CDR-IMGT regions of IG and TR is based on the IMGT unique numbering for all IG and TR V-REGIONs of all species: interest for structure and evolution and, for rearranged CDR3-IMGT and for FR4-IMGT, on the IMGT unique numbering for V-DOMAIN and V-LIKE-DOMAIN .

Overview

Anchor positions are positions which delimit the CDR-IMGT and which belong to the neighbouring FR-IMGT. They are shown in squares in the IMGT Colliers de Perles.

Anchor positions are:

FR1-IMGT CDR1-IMGT FR2-IMGT CDR2-IMGT FR3-IMGT For germline
V-GENE (*)
CDR3-IMGT
For rearranged
V-J-GENEs and
V-D-J-GENEs
Germline CDR3-IMGT Rearranged CDR3-IMGT FR4-IMGT
Amino acid
numbering
1 --> 26
(C 23)
27 --> 38 39 --> 55
(W 41)
56 --> 65 66 --> 104
(C 104)
105 --> 116 105 --> 117
(112.1, 111.1,
112.2, 111.2, etc.)
118 --> 129
Number of
amino acids
25-26 aa 5-12 aa 16-17 aa 0-10 aa 36-39 aa 2-12 aa 2-13 aa
(more than 13 aa)
10-12 aa

(*) + 0, 1 or 2 nucleotide(s) before the heptamer.

Note that positions of the codons (or amino acids) in the rearranged CDR3-IMGT are not equivalent to those in the germline CDR3-IMGT, and cannot therefore be directly compared.

FR-IMGT regions

CDR-IMGT regions

CDR-IMGT sequence and structural data comparison

See also: