SIX Homeobox Protein 2 (SIX2)

The vertebrate SIX genes are homologs of the Drosophila 'sine oculis' (so) gene, which encodes a nuclear homeoprotein required for eye development.The predicted 291-amino acid SIX2 protein contains a SIX domain and a homeodomain. The human SIX2 protein is almost identical to the mouse Six2 protein. Northern blot analysis of human tissues detected strong expression of a major 2.2-kb SIX2 transcript in skeletal muscle, with weaker expression in pancreas. RT-PCR showed SIX2 expression in all human fetal tissues tested except lung. In adult tissues, RT-PCR revealed SIX2 expression in skeletal muscle, pancreas, ovary, and sclera; SIX2 expression was not detected in other regions of the adult eye and optic nerve or in adult heart, lung, kidney, liver, or breast.