Chain A ( W18 T19 Y90 K92 L93 L94 G95 K96 G97 T98 F99 G100 K101 V102 I103 L104 A115 M116 K117 I118 L119 K120 V123 E129 H132 E136 L140 T149 L151 F163 V164 M165 A168 G170 G171 E172 L173 F174 F175 H176 D212 K214 L215 E216 N217 L218 M219 L220 K227 T229 D230 F231 G232 L233 T250 Y253 L285 T373 R374 Y375 F376 D377 E378 E379 F380 T381 )