The Gsc (goosecoid) gene family contains two genes in the human genome, one in amphioxus and one in Drosophila. Although Gsc genes are sometimes referred to as being Bicoid-like, this refers only to the presence of a lysine at homeodomain residue 50 in helix 3 (Gottlieb et al 1998) and not to high sequence similarity. Instead, the amino acid identity at this position has evolved independently: Gsc is a member of the PRD gene class, while Bicoid is a divergent Hox paralogy group 3 gene in the ANTP class. Despite the similar name, Gsc and Gsx genes are also very distantly related: the former in the ANTP class, the latter in the PRD class.|
Gottlieb S et al. (1998) Human Molecular Genetics 7: 1497-1505.