Chain A ( I429 L430 E431 P432 R433 S434 F435 L436 D437 K438 L439 S440 D441 Y442 Y444 G472 F473 Y474 K475 K476 P477 K478 G479 L480 K481 K482 P483 Y484 N485 P486 Q511 P517 S519 A538 K539 S540 K541 L547 S548 A549 I550 L551 Y572 A573 H574 C575 I578 M583 L585 E586 L587 W639 K706 )