Table 1.
Binding of ICAM-2 mutants to LFA-1 and ICAM-2 antibodies
| Mutant | Binding to LFA-1* | Binding to mAb†
|
Change in accessible surface, Å2 | Side chain H bonds | |||
|---|---|---|---|---|---|---|---|
| IC2/1 | IC2/2 | BT-1 | 6D5 | ||||
| ICAM-2 | 100 | 100 | 100 | 100 | 100 | 0 | |
| Q30/A | 107.9 ± 31 | 101 ± 3 | 44 ± 18 | ND | 130 ± 29 | −63 | |
| V33/A | 48.3 ± 11 | 126 ± 12 | 115 ± 13 | ND | 96 ± 44 | −8 | |
| G35/T | 2.3 ± 1 | 82 ± 6 | 78 ± 4 | 72 ± 4 | 117 ± 23 | ND | |
| E37/A | 1.3 ± 2 | 85 ± 16 | 83 ± 19 | ND | 86 ± 25 | −2 | |
| L40/A | 61.0 ± 23 | 95 ± 24 | 93 ± 20 | 104 ± 31 | 65 ± 35 | 40 | |
| N41/A | 57.6 ± 20 | 108 ± 33 | 103 ± 27 | 112 ± 31 | 82 ± 33 | −53 | |
| K42/A | 10.3 ± 14 | 62 ± 26 | 53 ± 27 | ND | 85 ± 48 | 15 | L36 O |
| I43/A | 94.0 ± 5 | 95 ± 7 | 94 ± 11 | 92 ± 11 | 156 ± 37 | −25 | |
| L44/A | 3.6 ± 3 | 39 ± 14 | 12 ± 2 | ND | 163 ± 100 | 10 | |
| L45/A | 1.2 ± 1 | 32 ± 18 | 18 ± 14 | 11 ± 8 | 62 ± 20 | 21 | |
| E47/A | 84.0 ± 7 | 79 ± 19 | 6 ± 3 | ND | 27 ± 18 | −20 | |
| Q48/A | 103.6 ± 13 | 86 ± 14 | 64 ± 15 | 82 ± 2 | 34 | −57 | |
| Q50/A | 107.6 ± 18 | 86 ± 25 | 83 ± 22 | ND | 168 ± 100 | −3 | N29 OD1 |
| K52/A | 13.5 ± 12 | 50 ± 6 | 31 ± 3 | 39 ± 2 | 51 ± 20 | 47 | G34 O |
| Y54/A | 4.4 ± 3 | 31 ± 1 | 5 ± 4 | 0 | 5 ± 6 | 70 | L36 N |
| L55/A | 98.2 ± 20 | 54 ± 4 | 64 ± 8 | 50 ± 16 | 40 | −21 | |
| S57/A | 114.3 ± 26 | 75 ± 22 | 67 ± 25 | 77 ± 20 | 78 ± 44 | 14 | |
| S60/A | 139.3 ± 32 | 65 ± 18 | 56 ± 24 | 64 ± 14 | 74 ± 24 | −12 | |
| D62/A | 100.2 ± 13 | 53 ± 16 | 41 ± 21 | 49 ± 7 | 78 | −31 | V84 N, R175 NH1 |
| Q66/A | 80.4 ± 24 | 99 ± 21 | 92 ± 18 | 97 ± 22 | 105 ± 59 | 1 | |
| H68/A | 0 ± 0 | 82 ± 25 | 76 ± 29 | ND | 151 ± 68 | 51 | |
| T70/A | 13.4 ± 9 | 71 ± 26 | 64 ± 25 | 58 ± 15 | 126 ± 26 | 17 | |
| Q75/A | 2.0 ± 2 | 88 ± 12 | 84 ± 32 | 72 ± 42 | 113 ± 20 | 6 | |
| S77/A | 104.0 ± 18 | 82 ± 10 | 85 ± 9 | 66 ± 6 | 76 | 6 | |
| N79/A | 93.2 ± 6 | 124 ± 50 | 119 ± 36 | 114 ± 45 | 130 ± 100 | −13 | L65 O |
| Q145/A | 103.1 ± 3 | 105 ± 21 | 102 ± 16 | 97 ± 12 | 97 ± 42 | 1 | |
| E146/A | 93.0 ± 14 | 74 ± 1 | 73 ± 0 | 88 ± 18 | 41 ± 12 | −13 | T114 N |
Binding to LFA-1 of ICAM-2 mutants (average ± SD for three experiments) was normalized to the amount of mutant ICAM-2 expression using a standard curve like that shown in Fig. 1A in each experiment. ICAM-2 expression was determined with CBR/IC2/1 mAb, except for three mutants with lowered binding of IC2/1 mAb, which were normalized with IC2/2 mAb.
Binding of mAb to mutants was normalized to the percentage of wild-type transfectants stained with the same mAb (average ± SD for three experiments, with some single determinations). The percentage of wild-type transfectants stained with IC2/1, IC2/2, BT-1, and 6D5 mAb averaged 37 ± 16%, 38 ± 16%, 34 ± 13%, and 9 ± 6%, respectively (average ± SD for 14 experiments). Residue numbering is revised based on recent determination of the beginning of the mature ICAM-2 sequence (11).