ILVF3 LIFV34 P36 LIVAF66 DE67 ILVM68 GC69 TCASV70 G71 ILVA75 DE92 AST101 NSIT104 DSNEGT138 IVTLC140 ND143 P144 P145 YF146 WIFLYV246 FYWHL248 # found 21 key residues