Chain A ( K225 Y228 Q230 W231 P232 L233 S234 D236 S325 Q326 K327 F328 K329 N330 K331 V332 S333 F335 I336 Q435 L438 S439 Y440 T441 C442 V443 C444 N445 R446 R447 L458 D459 D460 H461 E462 M463 V464 N465 L466 K467 Q468 Y469 S470 E471 L473 )