Summary of binding data and tyrosine sulfation status for the GPIbα mutants
| Mutant cell line . | AK2 . | Ristocetin . | Botrocetin . | Sulfation* . |
|---|---|---|---|---|
| D249N/D252N (Comb-3) | ↓↓ | NC | NA | NA |
| K253A/K258A/K262A (Comb-2) | ↓↓ | ↑ | NA | No |
| DEL | ↓↓ | ↓↓↓† | – | No |
| D269N | ↓↓↓ | ↓↓ | NA | Yes |
| E270Q | ↓↓↓ | ↓↓↓ | NA | No |
| D272N | ↓↓↓ | ↓↓↓↓ | NC | Yes |
| D274N | ↓↓ | NC | NC | NA |
| D277N | ↓↓↓ | ↓↓ | ↓↓↓↓ | Yes |
| D277A | ↓↓↓ | ↓↓ | ↓↓↓ | Yes |
| E281Q | ↓↓↓ | ↓↓ | ↓↓↓ | Yes |
| E282Q | ↓↓↓ | ↓↓↓ | ↓↓ | Yes |
| D283N | ↓↓↓ | ↓↓↓ | NC | No |
| E285Q | NC | ↓ | NC | Yes |
| D287N | ↓↓ | ↓↓ | NA | Yes |
| D283N/E285Q/D287N (Comb-1) | ↓↓↓ | ↓↓↓ | NA | No |
| Mutant cell line . | AK2 . | Ristocetin . | Botrocetin . | Sulfation* . |
|---|---|---|---|---|
| D249N/D252N (Comb-3) | ↓↓ | NC | NA | NA |
| K253A/K258A/K262A (Comb-2) | ↓↓ | ↑ | NA | No |
| DEL | ↓↓ | ↓↓↓† | – | No |
| D269N | ↓↓↓ | ↓↓ | NA | Yes |
| E270Q | ↓↓↓ | ↓↓↓ | NA | No |
| D272N | ↓↓↓ | ↓↓↓↓ | NC | Yes |
| D274N | ↓↓ | NC | NC | NA |
| D277N | ↓↓↓ | ↓↓ | ↓↓↓↓ | Yes |
| D277A | ↓↓↓ | ↓↓ | ↓↓↓ | Yes |
| E281Q | ↓↓↓ | ↓↓ | ↓↓↓ | Yes |
| E282Q | ↓↓↓ | ↓↓↓ | ↓↓ | Yes |
| D283N | ↓↓↓ | ↓↓↓ | NC | No |
| E285Q | NC | ↓ | NC | Yes |
| D287N | ↓↓ | ↓↓ | NA | Yes |
| D283N/E285Q/D287N (Comb-1) | ↓↓↓ | ↓↓↓ | NA | No |
Single-letter amino acid codes used in the table.
Arrows indicate increases or decreases in binding; NC, no change in binding compared to wild-type; −, no binding detected; and NA, not analyzed.
Yes indicates the recombinant cells have incorporated [35S], and no indicates no incorporation of [35S].
In the presence of ristocetin, the Del mutant bound less VWF at low ligand concentrations yet bound similar levels of VWF at high concentrations, compared to wild-type cells.