| VCY 2 protein interacts with the HECT domain of ubiquitin protein ligase E3A . ^^^ UBE3A contains a HECT domain that binds VCY 2 . ^^^ We also showed that both VCY 2 and UBE3A mRNAs were expressed in ejaculated human spermatozoa , indicating that both genes localize in the germ cell compartment . ^^^ These data suggest that UBE3A ubiquitination may be required for VCY 2 function . . ^^^ |