The RING-type zinc finger motif is present in a number of viral and eukaryotic proteins and is made of a conserved cysteine-rich domain that is able to bind two zinc atoms. Proteins that contain this conserved domain are generally involved in the ubiquitination pathway of protein degradation. SH3RF2 (SH3 domain containing ring finger 2), also known as RNF158, is a 729 amino acid protein with one RING-type zinc finger domain and three SH3 domains. Via its RING-type zinc finger domain, SH3RF2 binds an E2 ubiquitin-conjugating enzyme. This suggests that SH3RF2 functions as an E3 ubiquitin-protein ligase that accepts a ubiquitin residue from an E2 ubiquitin-conjugating enzyme and immediately transfers that residue to a protein that is targeted for degradation. Due to alternative splicing events, SH3RF2 is expressed as two different isoforms.