Chain A ( V3 R13 P14 P15 S16 K17 T18 Y19 R20 G21 A22 F23 Q24 N25 L26 F27 Q28 S29 V30 R31 E32 I232 S233 D234 N235 A236 K237 E238 L239 C240 K241 A242 V243 E710 L713 V714 V717 K718 K721 F726 V731 D732 D733 Q734 M735 A736 I738 Q739 Y740 L882 I883 S885 H886 D891 F892 P893 E894 M895 M896 A897 E898 I899 I900 S901 V902 Q903 P905 K906 )