A gene fragment of about 450 bp was amplified by PCR and the recombinant expression vector pGEX4T1-CRD was constructed, whose restriction maps and sequence were consistent with those of expected one.

• PCR扩增得到长约450bp的目的基因片段,插入pGEX4T1载体所获重组表达载体pGEX4T1CRD的酶切图谱和序列与预期的一致。