We have characterized a cDNA containing the coding region of a human SOX gene expressed in fetal brain. The cDNA is 1085 bp long, contains an open reading frame of 317 amino acids, and displays a high degree of similarity with the mouse Sox-2 gene. Human SOX2 has been local ized to the long arm of Chromosome (Chr) 3 in the region q26.3-27.
The mammalian sex-determining gene, SRY, encodes a protein that includes a sequence motif known as the HMG-box (Sinclair et al. 1990;Goodfellow and Lovell-Badge 1993). This motif is responsible for the different DNA-binding activities of the SRY protein, and mutation analysis suggests that a functional HMG-box is required for sex determination (Harley et al. 1992). The HMG-box motif is found widely in proteins that bind to DNA including transcription factors, proteins that bind to DNA with limited sequence specificity, and non-sequence-specific chromatin proteins (Ner 1992).
The mammalian genome contains a family of genes that are related to SRY in the region that encodes the HMGbox. These genes have been called SOX genes (SRY-related HMG-box genes). In the original report, four genes were identified as members of the mouse Sox gene family (Gubbay et al. 1990). These have been named Sox-1, Sox-2, Sox-3, and Sox-4 (previously referred to as al, a2, a3, and a4). All these genes are expressed during embryonic development as well as in some adult tissues; Sox-1, Sox-2, and Sox-3 are expressed at the highest levels in the developing nervous system (Collignon 1993). Subsequently, SOX genes have been identified in a wide variety of phylogenetically diverse organisms including mammals, birds, and insects. In most cases, the sequence information available is limited to the HMG-box (