The transcriptional enhancer factor (TEF)/TEAD family of proteins includes TEF-1, TEF-3, TEF-4 and TEF-5, all of which share a highly conserved 68 amino acid TEA/ATTS DNA-binding domain. TEF-5 (transcriptional enhancer factor-5), also known as TEAD3, TEAD5, DTEF-1 or ETFR-1, is a 435 amino acid nuclear protein that contains one TEA DNA-binding domain and belongs to the TEF transcriptional enhancer family. Expressed predominately in placental tissue and skeletal muscle, TEF-5 binds to multiple sites in the promotor of Placental lactogen II (also known as chorionic somatomammotropin-B) and, via this binding, enhances Placental lactogen II transcription. Due to its ability to enhance the expression of placenta-related genes, TEF-5 is thought to function as an important regulatory protein within the human placenta.