CD3G, also known as T-cell surface glycoprotein CD3 gamma chain, is associated on the T cell surface with a complex of protein called CD3. The protein is the CD3-gamma polypeptide, which together with CD3-epsilon, -delta and -zeta, and the T-cell receptor alpha/beta and gamma/delta heterodimers, forms the T-cell receptor-CD3 complex. This complex plays an important role in coupling antigen recognition to several intracellular signal transduction pathways. Defects in this gene are associated with T cell immunodeficiency. Recombinant human CD3G protein, fused to His-tag at C-terminus, was expressed in insect cell and purified by using conventional chromatography techniques.