Chain A ( L371 Q372 E373 V374 E375 V376 Q377 N378 E379 E380 M381 A382 A383 F384 L588 D654 L655 L656 R657 L658 H659 A660 N661 S662 G663 R664 S665 P666 T667 D668 C669 A670 Q671 K674 V676 L793 P794 L795 D797 F798 K799 F801 L802 T803 C804 G805 T806 K807 L808 Y810 P841 S842 P843 D846 I847 )