CHARACTERIZATION OF INCLUSION-BODIES IN RECOMBINANT ESCHERICHIA-COLI PRODUCING HIGH-LEVELS OF PORCINE SOMATOTROPIN

The protein composition of inclusion bodies (IBs) formed in recombinan t Escherichia coli producing high levels of porcine somatotropin (pST) was analyzed by one- and two-dimensional protein gel electrophoresis. Recombinant pST is exclusively recovered from the insoluble cell frac tion. Results indicate that, in addition to the main species of pST, s ubspecies with different isoelectric points and degradative fragments are contained within IBs. The presence of outer membrane proteins in I B fractions results from coprecipitation of cell debris during IB prep aration and not from specific in vivo or in vitro interaction of these proteins with IBs. Cells producing pST contain up to three IBs locate d in the cytoplasm. The implication of high level gene expression on t he uniformity of the desired product is discussed.