TABLE 2.
Summary of wild-type or mutant MBP-CR2 SCR1-2-gp350 binding ELISA dataa
| CR2 mutation | ELISA
|
Cell-binding assayb
|
||
|---|---|---|---|---|
| % gp350 binding by MBP-CR2 SCR1-2 (SEM) | Weighting | % gp350-biotin binding, MFI (SEM)b | Weighting | |
| L10A | 98.2 (5.1) | ++++ | NA | NA |
| N11A | 93.6 (0.6) | ++++ | 112.6 (11.6) | ++++ |
| R13A | 4.9 (0.1) | − | 7.0 (0.4) | − |
| S15P | 5.8 (0.5) | − | 5.4 (0.4) | − |
| Y16A | 95.1 (0.1) | ++++ | 66.7 (4.0) | ++ |
| R28A | 58.0 (5.6) | ++ | 21.9 (1.8) | + |
| S32A | 94.8 (1.0) | ++++ | 108 (12.9) | ++++ |
| T34A | 106.6 (5.4) | ++++ | NA | NA |
| R36A | 52.2 (3.1) | ++ | 29 (4.8) | + |
| K41A | 13.6 (0.7) | − | 20.8 (1.8) | + |
| K50A | 70.8 (11.4)c | +++c | 59.2 (1.9)c | ++c |
| K57A | 70.7 (2.3) | +++ | 36.5 (3.7) | + |
| Y64A | 93.6 (1.0) | ++++ | 84.5 (3.4) | +++ |
| K67A | 79.5 (7.4) | +++ | 42.1 (3.9) | +++ |
| Y68A | 87.5 (2.7) | ++++ | 111.4 (7.4) | ++++ |
| R83A | 32.1 (0.8) | + | 32.9 (4.9) | + |
| T86A | 91.9 (0.5) | ++++ | NA | NA |
| R89A | 56.1 (0.7) | ++ | NA | NA |
| M117A | 96.5 (4.1) | ++++ | NA | NA |
Given are percentages of gp350 binding to mutant CR2 relative to that of wild-type CR2. ++++, >90%; +++, 89.9 to 70%; ++, 69.9 to 40%;+, 39.9 to 20%; −, 19.9 to 0%.
Binding data and weighting were obtained from a previously reported cell-binding analysis of the CR2-gp350 binding interaction (46). NA, not applicable. Mutants indicated in boldface demonstrate a greater than 20% decrease in binding affinities relative to that of wild-type gp350 in both ELISA and the cell-binding assay (where available).
While the K50A mutant demonstrates a reduction in binding at the protein concentrations described in this table, at other values recorded for both the ELISA and cell-binding analyses, K50A binding approximates that of wild-type CR2 (Fig. 5) (1, 46). Residues (wild type) that have been underlined have been defined as active to drive the soft-docking study.