Androgen Induced Proliferation Inhibitor (APRIN)

In the prostate of adult mammals, most epithelial cells are in a state of proliferative quiescence. Androgens regulate this effect by inducing cell cycle arrest in the G0/G1 phase. The expression pattern of one of these sequences, designated AS3, strongly correlated with the expression of the androgen-induced proliferative shutoff both temporally and dosewise. The AS3 gene is upregulated during androgen-induced proliferative shutoff and induces cell proliferation arrest when expressed in a retrovirus transduced model. The deduced 1,391-amino acid AS3 protein has putative transactivating features, protein-protein interaction motifs (coiled coil and leucine zipper), and DNA-binding domains, suggesting that AS3 is a transcription factor. AS3 also has a protein-kinase motif, suggesting that it may act by phosphorylating a target protein.