These were at positions 126 (Ile or Thr or Ser) , 131 (Thr or Asn or Pro) , 133 (Met or Thr), 134 (Phe or Arg).

• AA131多为Thr,少数为天冬酰胺(Asn),1例为脯氨酸(Pro),AA133多为蛋氨酸,少数为Thr; AA134为苯丙氨酸,仅1例为精氨酸。