FoxP2: ProductsFoxP2 (Forkhead box protein P2; also CAGH44) is an 85-95 kDa member of the winged helix transcription factor gene family. It is a transcriptional repressor that is expressed principally in gut and lung epithelium, and in neurons involved in speech and language. Human FoxP2 is 715 amino acids (aa) in length. It contains a huge poly-Gln region (aa 123-231), a C2H2 Zn-finger domain (aa 346-371), a Leu-zipper segment (aa 388-409) and a forkhead DNA binding domain (aa 504-594). FoxP2 both homodimerizes and heterodimerizes with FoxP1 and P4, and binds CTBP1. There are multiple splice variants. There is an alternate start site at Met93, an 11 aa substitution for aa 57-715, a 25 aa insert after Gln86, an 11 aa substitution for aa 133-715, and a ten aa substitution for aa 423-715. Over aa 587-715, human and mouse FoxP2 are (100%) identical in aa sequence.