Biochemical characterization of murine leukaemia inhibitory factor produced by Krebs ascites and by yeast cells

Abstract

A cDNA library was constructed using mRNA from Krebs ascites tumor cells that was shown by Northern blot hybridization to contain mRNA for murine leukemia inhibitory factor (LIF). This library was screened with an oligonucleotide corresponding to the 3' end of a partial LIF cDNA clone, and an overlapping cDNA clone isolated. Nucleotide sequence analysis of this latter clone allowed the complete sequence of LIF to be derived. A cDNA molecule encoding the entire mature LIF protein was installed in a yeast expression vector, and LIF produced up to about 100 ng/ml in the growth medium. The LIF produced by yeast cells has the same biologic properties as native LIF and competes with native 125I-LI..