Structural and Biological Identity of Recombinant EDF (Erythroid Differentiation Factor) with Natural EDF

Abstract

EDF (Erythroid Differentiation Factor), which exhibits extensive differentiation inducing activity toward mouse Friend leukemia (MEL) cells, is produced by human THP-1 cells stimulated with TPA. The protein is a homo-dimer linked by disulfide bonds, the subunit of which has a molecular weight of 15.5 kd. We isolated cDNA clones encoding the 15.5 kd subunit of EDF and succeeded in the latter’s expression in Chinese Hamster Ovary (CHO) cells. That is, the CHO cells secreted a protein possessing differentiation inducing activity. This paper reports the identity of this protein, termed recombinant EDF (r-EDF), with the natural EDF from THP-1 cells as to molecular weight, isoelectric point, amino acid sequence of the N-terminal, amino acid composition, peptide map and the specific biological activity toward MEL cells.