Ubiquitination Factor E4B (UBE4B)

UBE4B encodes an additional conjugation factor, E4, which is involved in multiubiquitin chain assembly. This gene is also the strongest candidate in the neuroblastoma tumor suppressor genes. Alternatively spliced transcript variants encoding distinct isoforms have been found for this gene. UBE4B has a C-terminal U-box domain including a proline residue perfectly conserved among U-box proteins.  The deduced 903-amino acid protein shares weak similarity with Dictyostelium NOSA, a developmental regulator involved in proteasomal degradation of ubiquitinated proteins. Ufd2a interacted with Vcp, a AAA-family ATPase implicated in protein folding. the mouse Ube4b gene contains 27 coding exons.