PRODUCTION OF PROTEIN BY EXTRACELLULAR SECRETION

PURPOSE:To obtain protein by extracellular secretion, useful in the field of drugs, etc., simply and in high production efficiency, by cultivating a transformant transformed with a specific vector in a culture process at shifted pH. CONSTITUTION:Plasmid pTA529 and pHSI are conjugated to give a vector (e.g. pTA1529) which contains both a gene to code a promoter derived from alkali phosphatase and a gene to code signal sequence and can multiply in a host cell. then the vector is integrated with a gene to code human epidermal growth factor (hEGF) to give pTA1522 (figure), recombinant DNA. Then the pTA1522 is transduced to host Escherichia coli to give a transformant, which is cultivated in an inorganic phosphorus-containing medium at about 37 deg.C for about 20.5hr at pH 6.8-7 before protein synthesis ability is induced and at pH 7.4-7.8 after the protein synthesis ability is induced. Then hEGF, adventitious protein secreted in the medium is recovered.