Testicular Receptors

Testicular orphan receptors, testicular receptor 2 (TR2, also known as nuclear receptor subfamily 2, group C, member 2 (NR2C1)) and TR4 (NR2C2), are two evolutionarily related proteins belonging to the nuclear receptor superfamily. The domain organizations of both TR2 and TR4 are similar to those of many other NR family members. Located in the middle of the receptor is a DNA binding domain (DBD), and mapped to the C terminus is the ligand binding domain (LBD) with a ligand-inducible activation function region, AF-2. Located at the N terminus and upstream of the DBD is the N-terminal domain (NTD), including one or two activationfunction regions (AF-1), which is constitutively active for many nuclear receptors. TR2 and TR4 homodimerize and heterodimerize with each other but do not heterodimerize with retinoid X receptors (RXRs). TR2 and TR4 are expressed in spermatocytes, erythroid cells, liver, and some regions of the brain and are known to play important roles in spermatogenesis, lipid and lipoprotein regulation, and the development of the central nervous system.