Ubiquitin-like-conjugating enzyme ATG3 isoform 1, also known as ATG3, is an E2-like enzyme that localizes to the cytoplasm and is expressed in a variety of tissues with predominant levels found in kidney, placenta, liver, heart and skeletal muscle. ATG3 catalyzes the formation of the Atg8-phosphatidylethanolamine (ATG-PE) conjugate, a reaction that is essential for autophagy. Recombinant human ATG3 protien, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.