Chain A ( V161 F162 H163 Y164 R165 S166 A167 D169 R170 Y171 A172 H194 L195 Q196 A197 A198 F199 E200 D201 G202 F203 D204 N205 C206 D207 A208 G209 R217 Y218 P219 I220 T221 Q222 S223 R224 P225 G226 C227 Y228 G229 D230 R231 S232 S233 L234 P235 G236 V237 R238 Y240 D250 V251 Y252 C253 P306 D311 S313 V314 R315 Y316 P321 R322 R323 R324 C325 G326 G327 P328 A329 P330 G331 V332 R333 T334 V335 Y336 R337 F338 A339 N340 R341 T342 G343 F344 Y490 F491 Q494 P496 G502 G503 M504 E505 A506 S507 A508 Q509 P510 P511 T512 S513 E514 Q536 S537 R538 S539 P540 W541 A542 D543 L544 T545 N546 E547 V548 D549 M550 P551 G552 R637 G638 P639 H1127 N1148 D1149 R1150 I1151 V1152 E1153 R1154 D1155 F1156 Q1157 W1158 D1160 N1161 T1162 G1163 L1164 Q1165 F1166 E1167 K1231 Y1234 N1235 V1236 H1237 A1238 T1239 V1240 V1253 T1255 R1257 )