Synthesis of rat transferrin in Escherichia coli containing a recombinant bacteriophage

Using mRNA from rat liver a cDNA library was constructed in lambda gt11Amp3. Immunochemical screening identified 15 clones producing transferrin. The identity of two clones was confirmed by nucleotide sequencing, which also indicated a presegment rich in hydrophobic amino acids but lack of a prosegment in precursor transferrin. A 920 base pair insert in one clone corresponded to 84% of the N-terminal domain of transferrin, which was synthesized as a hybrid protein with bacterial beta-galactosidase. A 1540 base pair insert in another clone corresponded to the N-terminal plus 50% of the carboxy terminal domain of transferrin. The product of this clone possessed only antigenic properties of transferrin.