Chain A ( R147 F148 C150 I151 E152 V162 S163 L164 N165 R167 Y168 A227 A228 G229 I230 G231 K232 T233 I234 R237 Y258 H260 C261 R262 E263 V264 D302 G303 D305 E306 L307 Q308 R351 F373 Y381 F410 I411 P412 L413 V414 C415 W416 I417 V418 T420 Y443 F446 A473 A474 G476 I477 K481 I482 L483 F484 Q509 K510 E511 F517 Y518 S519 F520 I521 H522 M523 T524 F525 Q526 E527 K570 G571 )