Chain A ( P77 A78 S79 T80 F81 K82 M83 L119 G120 E121 A122 M123 K124 L125 S126 A127 V128 Y131 Q132 R136 D162 N163 W165 L166 V167 G168 E177 V181 M202 L203 L205 G215 K216 T217 G218 W219 A220 M221 D222 W229 L230 T231 G232 A256 R259 N260 )