E3 ubiquitin-protein ligase mediating 'Lys-48'-linked polyubiquitination of LIMK1 and its subsequent targeting to the proteasome for degradation. Negatively regulates axonal outgrowth through regulation of the LIMK1 turnover. Mediates 'Lys-6' and 'Lys-27'-linked polyubiquitination of AR/androgen receptor thereby modulating its transcriptional activity. May also bind DNA and function as a transcriptional regulator. S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Interacts with LIMK1 (By similarity). Interacts with AR. Localizes to the PML nuclear bodies in Sertoli cells. Weakly expressed in peripheral blood, spleen, prostate, testis and ovary. According to PubMed:18368307, it is preferentially expressed in testis and ovary and hardly detected in other tissues. Expressed in embryo and adult testis. The disease may be caused by variants affecting the gene represented in this entry. Required for prostate tumor cell growth. Belongs to the RNF12 family.