Consisting of about 110 amino acids, the domain in winged-helix transcription factors (see Regulation of gene expression) has four helices and a two-strand beta-sheet.
These proteins are classified into 19 families called FoxA-FoxS.
Mutations in FoxP proteins are implicated in human autoimmune diseases.
References
Winged-helix transcription factors Wikipedia(Text) CC BY-SA