UBE3A(Ubiquitin-protein ligase E3A) is also named as E6AP,EPVE6AP,HPVE6A and belongs to the E3 ubiquitin protein ligase family. It functions as both an E3 ligase in the ubiquitin proteasome pathway and as a transcriptional coactivator. It is also initially identified as a cellular protein that mediates in vitro association of the human papillomavirus E6 protein with p53,leading to the ubiquitin-dependent degradation of p53. Defects in UBE3A are a cause of Angelman syndrome (AS). It has 3 isoforms produced by alternative splicing.