Membrane androgen receptors (mARs) are a group of G protein-coupled receptors (GPCRs), which bind and are activated by testosterone and/or other androgens.[1][2][3] Unlike the androgen receptor (AR), a nuclear receptor which mediates its effects via genomic mechanisms, mARs are cell surface receptors which rapidly alter cell signaling via modulation of intracellular signaling cascades.[2][3] Known or proposed mARs include ZIP9 and GPRC6A.[2][4]
GPRC6A has been found to be involved in testicular function and prostate cancer.[2][3] mARs have also been found to be expressed in breast cancer cells.[5] Activation of mARs by testosterone has been found to increase skeletal muscle strength, indicating potential anabolic effects.[6] mARs have also been implicated in the antigonadotropic effects of androgens.[7] 3α-Androstanediol, an active metabolite of dihydrotestosterone (DHT) and a weak androgen as well as a neurosteroid via acting as a positive allosteric modulator of the GABAA receptor, rapidly influences sexual receptivity and behavior in animals, an effect that is GABAA receptor-dependent.[7]