Table 3.
Observed sequence differences in cAb VHH domains relative to VH domains. Underlined residues indicate new observations, and those which occur in most cAb VHH are summarized in boldface. cCamel or lllama residues observed only once. FRFramework or CDRComplementarity Determining Region.
| Chothia Residue Number | Amino Acids Present (Most/Some/Once) | Summary (Reported and Newly Discovered) | |
|---|---|---|---|
| Classical | cAbs | ||
| 11FR | -/LV/- | S/L/- | L→S10 |
| 14FR | P/-/AL | A/P/- | P→A, only two VHHs have P |
| 18FR | -/LV/- | L/-/- | [LV]→L |
| 23FR | K/AT/PQSV | -/AT/El Qc Sl | A, K most common in classicals; K absent in camelids |
| 29CDR | -/FILV/Y | -/ADFGINSVY/- | [FILV]→[DGNS],10 camelids more varied, 25% Y |
| 37FR | V/I/AF | F/VY/Dl | V→F,11 V→[FY]7 |
| 44FR | G/AKRS/E | E/GQ/Ac Dc | G→E,11 G→[EQ],12 [KR]→other |
| 45FR | -/L/F | R/L/Pl | L→R1. Occasional C reported in cDNA.10 |
| 47FR | -/W/LY | G/AFLSW/ Yl | W→G,11 W→[GSLF]12 |
| 49FR | G/AV/S | A/SV/Gl | G→A |
| 82FR | -/ILM/- | M/-/- | [ILM]→M, I occurs rarely |
| 84FR | S/ANT/- | P/S/Gl Ll Rc | S→P, only two VHHs have S |
| 87FR | -/ST/- | T/-/- | Camelids contain only T |
| 94FR | R/KS/GHPV | A/K/Gc Ic Tc Vl | R→non-charged, disrupts salt bridge to res. 10110 |
| 103FR | -/W/- | -/R,W/- | W→R9 |
| 105FR | -/AQT/HKR | Q/-/- | [AQT]→Q, Camelids contain only Q |
| 108FR | T/L,S/M | Q/-/Ec | [LTS]→Q |
| 109FR | V/L/- | V/-/- | L→V |