Chain A ( E540 I541 L542 D543 R544 D545 P546 L547 S548 Q549 L550 F569 P570 Q571 S572 L573 P574 K575 L576 L577 L578 L595 W598 L601 R604 E605 A606 L607 E608 L609 L610 D611 N613 Y614 A623 H996 G997 N998 L999 I1001 T1002 A1005 L1006 L1008 I1021 K1025 L1030 )