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. They share maximum homology within the HMG domain and are expressed mainly in the developing nervous system of the mouse (Collignon et al., 1996). These genes share significant homology outside the HMG box also and are highly conserved throughout their evolution. SOX11 appears to be important in the developing nervous system (SOX11 expression is detected from 8.5 dpc through to 13.5 dpc, with a considerable increase in expression by 13.5 dpc). SOX11 expression is apparent in the somites,limbs,facial mesenchyme,kidney,lung of the fetal system.