UbE3A (also called E6AP) is a 100 kDa HECT (homologous to E6AP carboxyl terminus) domain ubiquitin ligase containing two E2 binding sites for UbcH7 and UbcH8.UbE3A was found to bind to the human papillomavirus (HPV) oncoprotein E6 and mediate ubiquitination of p53.A frameshift mutation in the UbE3A gene leads to loss of function and causes Angelman Syndrome.