Chain A ( L2 G3 F4 E9 V12 Y13 V14 F16 L17 I147 A148 P149 F150 P151 T152 K153 F154 Y155 S156 S157 V158 V159 W160 G161 Y216 K219 Y220 V272 D273 P274 D275 T276 M277 K278 M280 R354 L355 C356 L357 Q358 F359 K360 L362 I417 R421 T427 A428 R431 )