Nerve Growth Factor IB - Evolution and Homology

Evolution and Homology

Nerve Growth factor IB has the systematic HUGO gene symbol NR4A1. It belongs to a group of three closely related orphan receptors, the Nur family, which has the symbol NR4A. The other two members are nuclear receptor related 1 protein (denoted by symbol NR4A2) and neuron-derived orphan receptor 1 (NR4A3).

NGFIB has a high degree of structural similarity with other family members at the DNA-binding domain with 91-95% sequence conservation. The C-terminal ligand-binding domain is conserved to a lesser extent at 60% and the N-terminal AB region is not conserved, differing in each member.

The three members are similar in biochemistry and function. They are immediate early genes activated in a ligand-independent manner that bind at the same sites on response elements.

NGFIB and the rest of the Nur family are structurally similar to other nuclear receptor superfamily members, but contain an extra intron. The DNA-binding domain at exons 3 and 4 of the NR4A1 gene is conserved among all members of the nuclear receptor.

NR4A1 has homologous genes in a range of species including neuronal growth factor-induced clone B in rats, Nur77 in mice and TR3 in humans.