The precursor form of the rat liver non-specific lipid-transfer protein, expressed in Escherichia coli, has lipid transfer activity

The cDNA encoding the precursor form or nonspecific lipid-transfer protein (pre-nsL-TP) from rat liver was cloned into the expression vector pET3d. The resulting plasmid was transformed to the Escherichia coli strain BL21(DE3). After induction or the bacteria with isopropyl-β-D-thiogalactopyranoside (IPTG) pre-nsL-TP was purified from the bacterial lysate by anion exchange chromatography followed by gelfiltration. From 1 1 or culture, 6–7 mg of pre-nsL-TP was obtained, equal to approximately 7% of the cytoplasmic protein. By use of a fluorescence lipid transfer assay, pre-nsL-TP was found to have lipid transfer activity identical to mature nsL-TP.