SOX1 expression is restricted to neuroectoderm in the tetrapod embryo. SOX1 is involved in early central nervous system development, where it is functionally redundant with SOX3 and to a lesser degree SOX2, and maintenance of neural progenitor cell identity. SOX1 is expressed particularly in the ventral striatum, and Sox1-deficient mice have altered striatum development, leading e.g. to epilepsy.The SRY and SOX proteins share a DNA-binding domain known as the HMG box, defined by a 79-amino acid region. All SOX proteins have a single HMG box and bind linear DNA in a sequence-specific manner, resulting in the bending of DNA through large angles. Bending causes the DNA helix to open for some distance, which may affect binding and interactions of other transcription factors. SOX1, SOX2, and SOX3 show the closest homology to SRY.