TEF (thyrotrophic embryonic factor), also known as KIAA1655, is a 303 amino acid nuclear transcription factor that belongs to the bZIP (basic region/leucine zipper) family and PAR (proline and acidic amino acid-rich) subfamily. TEF binds DNA as either a homodimer or heterodimer, and is known to transactivate the TSH beta promoter. While broadly expressed in adults, TEF is only found in developing embryonic anterior pituitary gland. TEF accumulates according to a robust circadian rhythm and has also been found to inhibit cell growth by downregulating beta chain expression of cytokine receptors. The functional domains of TEF are highly homologous with other members of the PAR-bZIP subfamily, including albumin D box-binding protein (DABP), human hepatic leukemia factor (HLF) and chicken vitellogenin gene-binding protein (VBP).
KIAA1655; Thyrotroph embryonic factor; thyrotrophic embryonic factor