T-cell surface glycoprotein CD3 zeta chain, also known as CD247, belongs to the CD3Z/FCER1G family. CD247 is T-cell receptor zeta, which together with T-cell receptor alpha/beta and gamma/delta heterodimers, and with CD3-gamma, -delta and -epsilon, forms the T-cell receptor-CD3 complex. The zeta chain plays an important role in coupling antigen recognition to several intracellular signal-transduction pathways. Low expression of the antigen results in impaired immune response. Recombinant human CD247 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.