APOC1 is a member of the apolipoprotein C family. This gene is expressed primarily in the liver, and it is activated when monocytes differentiate into macrophages. A pseudogene of this gene is located 4 kb downstream in the same orientation, on the same chromosome. It is mapped to chromosome 19, where it resides within an apolipoprotein gene cluster. Alternatively spliced transcript variants have been found for this gene, but the biological validity of some variants has not been determined. APOC1 has a length of 57 amino acids normally found in plasma and responsible for the activation of esterified lechitin cholesterol with an important role in the exchange of esterified cholesterol between lipoproteins and in removal of cholesterol from tissues. Its main function is inhibition of CETP, probably by altering the electric charge of HDL molecules. Recombinant human APOC1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.