E3 ubiquitin-protein ligase, which catalyzes ubiquitination of target proteins together with ubiquitin-conjugating enzyme E2 UBE2L3 (PubMed:16118314, PubMed:17646546, PubMed:19340006, PubMed:24076655). Acts as an atypical E3 ubiquitin-protein ligase by working together with cullin-5-RING ubiquitin ligase complex (ECS complex, also named CRL5 complex) and initiating ubiquitination of ECS substrates: associates with ECS complex and specifically mediates addition of the first ubiquitin on ECS targets (By similarity). The initial ubiquitin is then elongated (By similarity). E3 ubiquitin-protein ligase activity is activated upon binding to neddylated form of the ECS complex (PubMed:24076655). Mediates 'Lys-6', 'Lys-48'- and 'Lys-63'-linked polyubiquitination (PubMed:16118314, PubMed:17646546, PubMed:19340006). May play a role in myelopoiesis (PubMed:19340006). [E2 ubiquitin-conjugating enzyme]-S-ubiquitinyl-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-N(6)-ubiquitinyl-L-lysine. Autoinhibited by the ariadne domain, which masks the second RING-type zinc finger that contains the active site and inhibits the E3 activity (By similarity). Inhibition is relieved upon binding to neddylated cullin-RING ubiquitin ligase complexes, which activate the E3 ligase activity of ARIH1 (PubMed:24076655). Protein modification; protein ubiquitination. Interacts (via RING-type zinc finger 1) with UBE2L3 (PubMed:16118314, PubMed:19340006, PubMed:24076655). Interacts (via RING-type zinc finger 2) with UBE2N (PubMed:19340006). Interacts with neddylated CUL5 (PubMed:24076655). Interacts (via RING-type 2) with GFI1B (PubMed:17646546). Interacts with GFI1; prevents its ubiquitination and proteasomal degradation (PubMed:17646546). Interacts with DCUN1D1 (via UBA-like domain); promotes DCUN1D1 ubiquitination (PubMed:30587576). Widely expressed with higher expression in granulocytes. Up-regulated by all-trans retinoic acid (ATRA). Up-regulated during differentiation of immature blood cells toward monocytes and granulocytes. Members of the RBR family are atypical E3 ligases. They interact with the E2 conjugating enzyme UBE2L3 and function like HECT-type E3 enzymes: they bind E2s via the first RING-type zinc finger, but require an obligate trans-thiolation step during the ubiquitin transfer, requiring a conserved active site Cys residue in the second RING-type zinc finger. The active site probably forms a thioester intermediate with ubiquitin taken from the active-site cysteine of the E2 before ultimately transferring it to a Lys residue on the substrate. The Ariadne domain inhibits activity by masking the second RING-type zinc finger that contains the active site. Ubiquitinated. Ubiquitination promotes proteasomal degradation. Belongs to the RBR family. Ariadne subfamily.