Matrix of similar interfaces for 3D-footprint entry 4b21_A

_ stats: contacts=6 Nring=5 specif=0.83
_ PDBs:  1:4ejy_A,2:8dvp_A,
_ -lnE:  1:24.7,2:16.9,
_        1 2
0051 K* NGQG
0053 S* RGRG
0094 S* --YC
0096 L* FG--
0097 K* RC--
0179 T  --PA