The germ cell nuclear factor (GCNF) protein, also known as RTR (retinoid receptor-related testis-associated receptor), is a member of the nuclear receptor family of intracellular transcription factors and is encoded by the NR6A1 gene (nuclear receptor subfamily 6, group A, member 1).In adults, GCNH is expressed mainly in the germ cells of gonads and is involved in the regulation of embryogenesis and germ cell differentiation.
Its expression pattern suggests that it may be involved in neurogenesis and germ cell development. The protein can homodimerize and bind DNA, but in vivo targets have not been identified. The gene expresses three alternatively spliced transcript variants.