methods : an artificial gene for fl extracellular domain cdna was synthesized by using favored genetic codons of pichia pastroris . by inserting human fl extracellular domain cdna coding 156 amino acid resi dues into pichia pastoris expression vector ppic9k containing aox1 promoter and the sequences of alpha secreting signal peptides, a recombinant expression plasmid ppic9k-fl was constructed, and integrated into the alcohol oxidase region of the host genome 為了提高外源基因的表達量,我們根據(jù)畢赤氏酵母偏愛密碼子人工合成了編碼fl胞外區(qū)156個氨基酸的cdna序列,目的序列被定向克隆到酵母分泌型表達載體ppic9k質(zhì)粒上,構建ppic9k-fl表達質(zhì)粒。