– WWP2 contains 1 C2 domain, 1 HECT (E6AP-type E3 ubiquitin-protein ligase) domain and 4 WW domains. It is an E3 ubiquitin-protein ligase that accepts ubiquitin from an E2 ubiquitin-conjugating enzyme in the form of a thioester and then directly transfers the ubiquitin to targeted substrates. WWP2 can be detected in heart, throughout the brain, placenta, lung, liver, muscle, kidney and pancreas. It is also expressed in spleen and peripheral blood leukocytes. WWP2 polyubiquitinates POU5F1 by ‘Lys-63’-linked conjugation and promotes it to proteasomal degradation; in embryonic stem cells (ESCs) the ubiquitination is proposed to regulate POU5F1 protein level. WWP2 ubiquitinates EGR2 and promotes it to proteasomal degradation; in T-cells the ubiquitination inhibits activation-induced cell death. It also ubiquitinates SLC11A2; the ubiquitination is enhanced by presence of NDFIP1 and NDFIP2. WWP2 ubiquitinates RPB1 and promotes it to proteasomal degradation.