A cell-free protein synthesis system from insect cells.

The Transdirect insect cell is a newly developed in vitro translation system for mRNA templates, which utilizes an extract from cultured Spodoptera frugiperda 21 (Sf21) insect cells. An expression vector, pTD1, which includes a 5'-untranslated region (UTR) sequence from a baculovirus polyhedrin gene as a translational enhancer, was also developed to obtain maximum performance from the insect cell-free protein synthesis system. This combination of insect cell extract and expression vector results in protein productivity of about 50 microg/mL of the translation reaction mixture. This is the highest protein productivity yet noted among commercialized cell-free protein synthesis systems based on animal extracts.