Red sea bream growth hormone (rsbGH) was produced using a secretion plasmid which con-sisted of the signal sequence of E. coli β-lactamase and a cDNA of rsbGH. In the periplasmic space of E. coli cells harboring the secretion plasmid, three isofroms of GH that were immunoreactive to anti-salmon GH serum and had a molecular weight of approximately 22, 000 were found. One of the immunoreactive GH was shown to be physicochemically identical to the natural rsbGH in the pituitary extract of red sea bream, having pyroglutamic acid at the N-terminus and an isoelectric point of 6.2. Receptor binding activity of the purified recombinant rsbGH was confirmed by using the membranes of red sea bream liver.
