Chain A ( L248 F292 R294 H295 M296 S298 F307 G308 L309 Y311 G312 I313 S314 P315 S316 Y317 M318 I321 H466 L473 I475 A487 L488 T489 D490 H491 T492 D493 L494 M495 T496 T497 A509 S510 S513 Q514 G515 Q516 D517 L518 F519 N520 Q522 R523 R524 H525 Y526 W527 V528 T529 A530 A531 D534 T535 L536 A537 I538 T539 T540 P541 L545 L547 N548 N549 Q569 L570 S571 L572 )