HERC5 is a member of the HERC family of ubiquitin ligases. It is a protein with a HECT domain and five RCC1 repeats. The protein localizes to the cytoplasm and perinuclear region and functions as an interferon-induced E3 protein ligase that mediates ISGylation of protein targets. HERC5 gene lies in a cluster of HERC family genes on chromosome 4. It has been shown to exhibit antiviral activity towards HIV-1, influenza A virus and human papillomavirus. Recombinant human HERC5 protein, fused to His-tag at N-terminus, was expressed in E.coli.