E3 ubiquitin-protein ligase that cooperates with the microRNAs (miRNAs) machinery and promotes embryonic stem cells proliferation and maintenance (Probable). Binds to miRNAs and associates with AGO2, participating in post-transcriptional repression of transcripts such as CDKN1A (By similarity). In addition, participates in post-transcriptional mRNA repression in a miRNA independent mechanism (PubMed:23125361). Facilitates the G1-S transition to promote rapid embryonic stem cell self-renewal by repressing CDKN1A expression. Required to maintain proliferation and prevent premature differentiation of neural progenitor cells during early neural development: positively regulates FGF signaling by controlling the stability of SHCBP1 (By similarity). Specific regulator of miRNA biogenesis. Binds to miRNA MIR29A hairpin and postranscriptionally modulates MIR29A levels, which indirectly regulates TET proteins expression (PubMed:28431233). 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 (via NHL repeats) with AGO2; the interaction increases in presence of RNA (PubMed:23125361). Interacts with HSP90AA1. Interacts (via NHL repeats) with MOV10, PABPC1, PUM1, PUM2, STAU2, XRN1 and XRN2 in an RNA-dependent manner (PubMed:23125361). Interacts with SHCBP1; leading to enhance its stability (By similarity). Specifically expressed in testis. Negatively regulated by the microRNA (miRNA) let-7 which causes degradation of the mRNA encoding this protein. This requires a let-7 complementary site (LCS) in the 3'-UTR of the mRNA encoding this protein (PubMed:17890240, PubMed:24239284). Down-regulated by retinoic acid in Tera-2 cells (PubMed:15722555). The NHL domain, containing the 6 NHL repeats, is necessary and sufficient to target RNA but not to repress mRNA. The minimal region needed to execute repression consists of the coiled coil domain and the Filamin repeat. The RING-type domain is dispensable for mRNA repression. Autoubiquitinated. The disease is caused by variants affecting the gene represented in this entry. Promotes reprogramming of differentiated cells to an embryonic-like state designated iPS (induced pluripotent stem) cells. iPS cells exhibit the morphology and growth properties of ES cells and express ES cell marker genes. Inhibits translation of the prodifferentiation transcription factor EGR1 through binding to its mRNA and regulates a broad array of differentiation genes. Belongs to the TRIM/RBCC family.