TABLE 1.
Human FcRn binding to various anti-CD20 IgGs including cysteine loop and charged loop library variants
| Variant | Sequence (432–437)a | pH 6.0 KDb | pH 7.4 KDb | Notes |
|---|---|---|---|---|
| nm | nm | |||
| Wild type | LHNHYT | 880 | >10,000 | Anti-CD20 IgG1 (28) |
| YTE | LHNHYT | 215 | 5750 | (M252Y, S254T, T256E) (11) |
| N3E-YTE | CSWHLCEc | 4 | 41 | Original construct identified from phage panning (contains glutamine insertion after residue 437) |
| N3-YTE | CSWHLC | 24 | 353 | Glutamine insertion removed from N3E-YTE |
| N3E | CSWHLCE | 49 | 1260 | YTE removed from N3E-YTE |
| CwtC-YTE | CHNHYC | 367 | 7700 | L432C, T437C, YTE |
| C83-YTE | CRRHICE | 160 | 6650 | Cysteine loop library |
| C37-YTE | CSRHRCE | 225 | 10,000 | Cysteine loop library |
| C56-YTE | CRRHSCE | 364 | >10,000 | Cysteine loop library |
| C59-YTE | CNRHRCE | 737 | >10,000 | Cysteine loop library |
| Y3-YTE | ERYHTQ | 36 | 2640 | Charged loop library |
| Y31-YTE | ERFHRQ | 57 | 4730 | Charged loop library |
| Y12-YTE | EAWHRQ | 34 | 6970 | Charged loop library |
| Y83-YTE | ERFHSQ | 120 | >10,000 | Charged loop library |
| Y53-YTE | ERFHTQ | 68 | 5460 | Charged loop library |
| Y43-YTE | EPHHRQ | 152 | >10,000 | Charged loop library |
| Y34-YTE | HTHHRQ | 187 | >10,000 | Charged loop library |
| Y39-YTE | EPWHYQ | 25 | 947 | Charged loop library |
| Y37-YTE | HRFHLQ | 179 | 1520 | Charged loop library |
| Y38-YTE | EQFHRQ | 152 | >10,000 | Charged loop library |
a Residue numbering is according to Kabat et al. (30).
b Steady-state affinity measurements carried out by ProteOn as described under “Experimental Procedures.” Values in italic type were determined via kinetic model (Langmuir with mass transfer).
c Boldface type indicates insertion residue 437*.