Expressed mainly in the testis. Also expressed in the brain where they are enriched at the postsynaptic sites. Expressed at lower levels in the trachea, prostate, bone marrow, spinal cord, colon, fetal brain, heart, thymus, fetal liver, spleen, leukocytes, ovary, small intestine, pancreas and skeletal muscle. Expression is significantly lower in testicular cancer tissues than in normal testicular tissues. Isoform 3 is expressed in the testis, trachea, prostate and bone marrow.
Up-regulated by mibolerone (a synthetic androgen) and dihydrotestosterone (DHT) and is down-regulated by estrogen and progestin.