Chain A ( Y48 M425 Q455 C472 S473 G474 P475 G476 L477 P478 L504 M509 P510 S511 K512 K513 L514 Q527 M528 I529 L530 L543 L544 D545 Q553 K554 A555 D556 T557 V558 F559 R560 L561 N562 W563 A564 T565 I574 V575 A576 S577 F578 D579 )