pFastBac1载体是非融合性蛋白表达载体，在载体内部不带有其他融合性的蛋白标签。为了保证目的基因的正确表达，插入片段必须包含ATG起始密码子，保证蛋白起始翻译。插入片段最好包含终止密码子，保证蛋白质不会翻译出多余的氨基酸。在pFastBacI载体多克隆位点中，对于所有的三种读码框分布，都包含有终止密码子。
   The Bac-to-Bac® Vector Kit contains a pFastBac™ 1 vector, as well an expression control vector, intended for use as part of the Bac-to-Bac® Baculovirus Expression System , which enables the efficent production of recombinant baculovirus for expression testing in insect cells. The Bac-to-Bac® System relies on generation of recombinant baculovirus by site-specific transposition in E. colirather than homologous recombination in insect cells (Figure 1). This system features:
   Time-saving expression bacmid. With Bac-to-Bac®, the expression cassette of the pFastBac™ vector recombines with the parent bacmid in DH10Bac™ E. coli Competent Cells (not included with this vector kit) to form an expression bacmid. The bacmid is then transfected into insect cells for production of recombinant baculovirus particles.
   Easy colony screening. The parent bacmid in DH10Bac™ E. colicontains a segment of the lacZα gene. The lacZα gene is disrupted upon transposition of the expression cassette into the bacmid allowing for blue/white selection of recombinants. This makes identification  of recombinant colonies easy.