Table 1. Characteristics of CDTa-specific and CDTb-specific families of nanobodies.
| specificity | llama | family | isolates | variants | CDR3 | affinity (Kd) | epitope | IC50 tox | IC50 ART | |
|---|---|---|---|---|---|---|---|---|---|---|
| CDTa | 6 | l+8 | 2 | 1 | ECGGYGAH | 1 nM | 1 | 2 nM | 2 nM | |
| 6 | l-14 | 2 | 1 | TYRPNTFTPAEYDY | 1.5 nM | 2 | > 1 µM | 4 nM | ||
| 6 | l-15 | 4 | 2 | GGFTEAYSGTYYPDS | 1.5 nM | 3 | > 1 µM | 4 nM | ||
| 6 | l+18 | 8 | 5 | GGSGYGCYAFTPAYGMDY | 1.5 nM | 2,3 | 50 nM | 4 nM | ||
| 5037 | s-21 | 18 | 4 | ADQRVGYIEYYSGSSGKEYDY | 3 nM | 2,3 | 50 nM | 4 nM | ||
| CDTb | 180 | l-3 | 13 | 9 | RGY | > 50 nM | 1 | > 1 µM | - | |
| 180 | l-15.1 | 13 | 10 | KVGANILTRSIGYKY | 0.5 nM | 1 | 4 nM | - | ||
| 180 | l-15.3 | 1 | 1 | TNKBYTDGRLEEYDY | 9 nM | 2 | > 1 µM | - | ||
| 180 | l-19 | 1 | 1 | DGRSNLRANYDSADYGMAY | 15 nM | 3 | > 1 µM | - | ||
Family names indicate the presence of a short (s) or long hinge (l), the absence (-) or presence (+) of a disulfide bond connecting CDR2 and CDR3, and the length of the CDR3 in numbers of amino acid residues. Isolates indicates the number of clones selected per family, variants indicates the number of clones carrying distinct but evidently related amino acid sequences. Variant amino acid positions in the CDR3 are indicated in red. Epitopes are numbered arbitrarily (nanobodies that block the binding of one another are considered to recognize the same or overlapping epitopes). “IC50 tox” indicates the nanobody concentration required to inhibit 50% rounding of HT29 cells upon incubation with 2 nM CDTa+b for 4 h at 37°C. “IC50 ART” indicates the nanobody concentration required to inhibit ADP-ribosylation of actin by 2 nM CDTa by 50%.