PRODUCTION OF THE BETA-SUBUNIT OF HUMAN CHORIONIC-GONADOTROPIN IN ESCHERICHIA-COLI AND ITS EXPORT MEDIATED BY THE HEAT-LABILE ENTEROTOXIN CHAIN-B SIGNAL SEQUENCE

The PCR-amplified beta-subunit of the human chorionic gonadotropin str uctural gene (beta hCG) was cloned under the control of the tac promot er and the heat-labile enterotoxin chain B (LTB) signal sequence (LTBs s), beta hCG was successfully produced, processed and exported to the periplasmic space in Escherichia coli. Expression of beta hCG was conf irmed by immunoblot analysis using an anti-beta hCG polyclonal antibod y. The processing of the protein was very efficient, as only the proce ssed band could be detected at all time points during the course of in duction, Expression was evident soon after the addition of the lactose analogue, IPTG. These results demonstrate that E. coli cells can synt hesize, process and export beta hCG using the LTBss.