Kabat Antibody Numbering
abYsis supports all major numbering systems. The Kabat numbering scheme is the most widely adopted standard for numbering residues in an antibody in a consistent manner.
Kabat Details
Despite its global popularity, the Kabat scheme is now known to have limitations:
In the potentially very long CDR-H3, insertions are numbered between residue H100 and H101 with letters up to K (i.e. H100, H100A ... H100K, H101).
We now know it is possible to have more residues than that, but there is no standard way of numbering them. A similar situation can occur at other positions too.
The Kabat numbering scheme was developed from sequence data (a fairly limited set), without the knowledge of structure.
We now know that the position at which insertions occur in CDR-L1 and CDR-H1 does not actually match the structural insertion position.
Thus topologically equivalent residues in these loops do not get the same number.
Numbering using the Kabat system is as follows:
Light chain
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27
27A 27B 27C 27D 27E 27F 28 29
30 31 32 33 34 35 36 37 38 39
40 41 42 43 44 45 46 47 48 49
50 51 52 53 54 55 56 57 58 59
60 61 62 63 64 65 66 67 68 69
70 71 72 73 74 75 76 77 78 79
80 81 82 83 84 85 86 87 88 89
90 91 92 93 94 95
95A 95B 95C 95D 95E 95F 96 97 98 99
100 101 102 103 104 105 106
106A 107 108 109
Heavy chain
0 1 2 3 4 5 6 7 8 9
10 11 12 13 14 15 16 17 18 19
20 21 22 23 24 25 26 27 28 29
30 31 32 33 34 35
35A 35B 36 37 38 39
40 41 42 43 44 45 46 47 48 49
50 51 52
52A 52B 52C 53 54 55 56 57 58 59
60 61 62 63 64 65 66 67 68 69
70 71 72 73 74 75 76 77 78 79
80 81 82
82A 82B 82C 83 84 85 86 87 88 89
90 91 92 93 94 95 96 97 98 99
100
100A 100B 100C 100D 100E 100F 100G 100H 100I 100J
100K 101 102 103 104 105 106 107 108 109
110 111 112 113
For more information, visit the web site of our collaborator Professor Andrew Martin, from which the information here was adapted: www.bioinf.org.uk/abs