Androgen R/NR3C4: ProductsHuman Androgen Receptor (AR; NR3C4) is a 110 kDa member of the NR3 subfamily of the nuclear hormone receptor family. Androgen receptors are expressed by androgen-sensitive tissue (bone, prostate, testis) and exist as both ahomodimers and a heterodime in a complex with the glucocorticoid receptor. Multiple forms of the androgen receptor are known to exist. The 110 kDa 'B' form is 919 amino acids in length. Phosphorylation increases its molecular weight to 112 kDa and 114 kDa. A five amino acid deletion (amino acids 74 - 78) in AR-B has been reported. In addition, a short 'A' form of 87 kDa and 732 amino acids is also known. Expanded polyglutamine repeats in the androgen receptor are known to cause Kennedy's disease, an X-linked form of motor neuron disease.