Chain A ( N52 S103 G104 G105 V106 Y107 S108 M109 I122 G123 L124 L125 Y126 V127 F128 G129 Q130 C131 A133 G134 Y137 L168 V176 K177 A249 F251 N252 M253 G254 D256 L257 S320 A322 S323 C324 M325 G326 G327 L328 Y329 G330 A331 P332 R333 I334 L335 Q336 C337 I338 A339 Q340 T367 V370 T371 N390 F391 T394 )