TABLE 1.
Summary of wild-type CR2 binding to mutant forms of gp350a
| gp350 mutation | ELISA
|
Cell-binding assay
|
||
|---|---|---|---|---|
| % gp350 binding by MBP-CR2 SCR1-2 (SEM) | Weighting | % gp350-biotin binding, MFI (SEM) | Weighting | |
| E21A | 65.6 (7.6) | ++ | 57.6 (3.2) | ++ |
| D22A | 5.2 (0.1) | − | 44.6 (3.4) | ++ |
| D53A | 89.3 (1.1) | +++ | 90.8 (2.6) | ++++ |
| E119A | 101.5 (0.1) | ++++ | 80.4 (5.3) | +++ |
| Y151A | 16.1 (1.5) | − | 57.5 (0.2) | ++ |
| E155A | 28.5 (1.4) | + | 67.6 (3.8) | ++ |
| Y159A | 82.8 (3.4) | +++ | 94.8 (2.6) | ++++ |
| I160A | 10.4 (8.3) | − | 50.1 (5.5) | ++ |
| W162A | 15.7 (8.9) | − | 13.3 (2.7) | − |
| D163A | 86.7 (1.4) | +++ | 83.7 (0.7) | +++ |
| E201A | 63.5 (2.5) | ++ | 103.9 (3.4) | ++++ |
| D208A | 34.5 (2.5) | + | 68.2 (12.3) | ++ |
| E210A | 41.6 (1.2) | ++ | 63.6 (4.2) | ++ |
| E214A | 98.7 (1.4) | ++++ | 76.2 (0.8) | +++ |
| D215A | 64.4 (1.4) | +++ | 86.5 (14.4) | +++ |
| E236A | 101.2 (1.1) | ++++ | 90.6 (4.6) | ++++ |
| D296A | 10.3 (0.4) | − | 61.4 (2.0) | ++ |
Given are the percentages of the CR2 binding of single-site mutant forms of gp350 relative to those of wild-type gp350 from both ELISA and cell-binding analyses. ++++, >90%; +++, 89.9 to 70%; ++, 69.9 to 40%; +, 39.9 to 20%; −, 19.9 to 0%. MFI, mean fluorescent intensity. Data are reported for concentrations of 2 μg/ml of MBP-CR2 SCR1-2 and 5 μg/ml of gp350 for the ELISA study and 5 × 105 full-length CR2-transfected K562 cells and 5 μg/ml of gp350-biotin for the cell-binding study. Mutants indicated in boldface demonstrate a greater-than 20% decrease in binding affinities relative to those of wild-type CR2 in both ELISA and the cell-binding assays. Residues (wild type) that have been underlined have been defined as active for the purposes of the soft-docking study.