FOX3/NeuN

Fox3 is one of a family of 3 mammalian Fox homologues. Fox was discovered in C. elegans as a gene involved in sex determination, and the name Fox is an acronym of "Feminizing locus on X". The Fox protein and its 3 mammalian homologues are all about 46kDa proteins each of which includes a central highly conserved RRM type RNA recognition motif, which corresponds to a small ~70 amino acid structure consisting of 4 beta strands and two alpha-helices. An alternate name for Fox 3 is hexaribonucleotide binding protein 3, and these proteins are believed to have a role in the regulation of mRNA splicing.

Much interest has focused on Fox3 as this protein corresponds to NeuN, a neuronal nuclear antigen. NeuN antibody has become very widely used as a robust marker of neurons and neuronal stem cells. Fox3 is therefore a protein which has a funciton in RNA splicing and is expressed heavily and specifically in neuronal nuclei.