Expression analysis of a modified Factor X in stably transformed insect cell lines

A modified Factor X protein was combined with a cellulose-binding domain ta g and expressed in insect cell fines. The protein, CBDFX, was expressed and secreted into the medium. Stable, transformed Hi5 and Sf9 insect cell line s were generated and tested for production of secreted CBDFX. The highest S f9 and Hi5 CBDFX-producing cell lines were scaled up to 2-liter fermentors to evaluate production of this recombinant protein. Secreted protein produc tion levels reached 4 mg/liter for the stable, transformed Hi5 cell line an d 18 mg/liter for the stable, transformed Sf9 cell line. The protein was pr operly processed as determined by amino terminal sequencing and bound well to the cellulose substrate Avicel. In addition the activated recombinant CB DFXa was capable of recognizing and efficiently processing a Factor X cleav age site. (C) 2001 Academic Press.