Double Homeobox Protein 3 (DUX3)

The human genome contains hundreds of repeats of the 3.3-kb family in regions associated with heterochromatin. The DUX gene family, including DUX3, resides within these 3.3-kb repeated elements. The deduced DUX3 protein contains 2 homeoboxes and shares 98% identity with DUX1 and DUX5. Both DUX3 and DUX5 sequences contain an additional start site encoding a deduced N-terminal extended isoform. Using in vitro transcription/translation, they confirmed the presence of the shorter deduced DUX3 protein and N-terminal extended isoforms. Northern blot analysis of multiple human tissue cDNAs derived from poly(A)-positive RNA failed to detect DUX3 transcripts; however, RT-PCR of total RNA from human heart and fetal liver, as well as human fetal kidney and human hepatoma cells, detected several DUX3/DUX5-related transcripts.