Table 2

Comparison of affinities between the wild type (WT) and the L240A mutant BRDG1 SH2 domain for peptides containing a hydrophobic residue at P+3 or P+4. Each peptide contains a fluorescein label coupled to the N terminus through a Gly-Gly dipeptide or an ahx residue. Relative affinity is defined as the ratio of the Kd value of the wild type over that of a mutant SH2 domain. Kd, dissociation constant determined from fluorescence polarization measurements.

Peptide sequenceKd ± SE (μM)Relative
affinity (a/b)
WT (a)L240A (b)
P+4 hydrophobic peptides
H-Q-L-pY-D-D-S-F-P-M-NH21.76 ± 0.099.17 ± 0.610.2
Q-D-T-pY-E-T-H-L-E-T-NH20.12 ± 0.011.01 ± 0.050.1
R-N-D-pY-D-D-T-I-P-I-NH20.32 ± 0.023.08 ± 0.220.1
Y-Q-H-pY-D-L-D-L-K-D-NH20.58 ± 0.035.59 ± 0.260.1
P+3 hydrophobic peptides
T-Y-K-pY-D-L-F-S-D-NH221.03 ± 2.622.88 ± 0.187.3
P-Q-P-pY-E-F-F-S-E-NH219.94 ± 1.715.25 ± 0.533.8
L-T-I-pY-E-D-V-K-D-L-NH238.80 ± 6.589.59 ± 0.844.0
N-T-V-pY-S-E-V-Q-F-A-NH239.82 ± 5.5210.12 ± 0.653.9
P+3 scanning peptides
E-E-E-pY-S-E-W-K-E-L5.79 ± 0.680.48 ± 0.0312.1
E-E-E-pY-S-E-F-K-E-L-NH24.87 ± 0.260.49 ± 0.0210.0
E-E-E-pY-S-E-L-K-E-L8.08 ± 1.111.57 ± 0.115.2
E-E-E-pY-S-E-A-K-E-L14.64 ± 1.476.63 ± 0.702.2
E-E-E-pY-S-E-Y-K-E-L11.12 ± 1.035.17 ± 0.372.2