A polymerase-chain-reaction product coding for the mature growth hormoneof yellowfin porgy(ypmGH cDNA)fused to the leader sequence of yeastprepro-α-factor was constructed in 2 μm plasmid vector.The chimeric plasmidwas designated as pMAyp.Recombinant growth hormone(rGH)of fish wasfound in the culture medium of Saccharomyces cerevisiae 20B12 harboring pMAyp.The secreted rGH migrated on the SDS-polyacrylamide gel with the sameelectrophoretic mobility as the authentic GH,at about molecular weight of 22kilo-daltons.As expected,this band was absent in the culture supernatant ofstrain contained expressing vector,pMA56/α,without insertion of ypmGH cDNA.