Abstract: Phage Display Technique was developed in 1985, it were applied in various biological fields. Phage can be exploited to display peptides, protein domains and even whole protein on its surface. Gene 3 protein and gene 8 protein are both the coat proteins of filamentous bacteriophage. Both of them were synthesized by using the precursors(pre-coats). Through different transmembrane pathways, they were inserted into the inner membrane of Escherichia coli cell and cleaved into mature proteins by the leader peptidase. To investigate the importance of the leader peptides, a small peptide was incorporated into the N-terminal region of gene 8 protein by using gene engineering methods. And for the first time, the leader peptide was deleted or replaced with the leader peptide of gene 3 protein. Pulse-chase analysis demonstrates the effects of different leader peptides on the polypeptide displayed on the N-terminal of gene 8 protein. The results showed that the precursor couldn't be converted into mature coat protein without the aid of leader peptide, while the leader peptide of gene 3 protein made gene 8 protein containing a foreign peptide become mature protein. These results have an important significance for the further studies of transmembrane mechanism of coat proteins of filamentous bacteriophage in E. coli.

Key words: Gene 8 protein, Leader peptide sequence, Phage display, Foreign peptide