Rcat domain found in RING finger protein 19B (RNF19B)
RNF19B, also called IBR domain-containing protein 3, or natural killer (NK) lytic-associated molecule (NKLAM), is a transmembrane (TM) domain-containing RBR-type E3 ubiquitin-protein ligase that plays a role in controlling tumor dissemination and metastasis. It is involved in the cytolytic function of NK cells and cytotoxic T lymphocytes (CTLs). It interacts with ubiquitin conjugates UbcH7 and UbcH8, and ubiquitinates uridine kinase like-1 protein, targeting it for degradation. Moreover, RNF19B is a novel component of macrophage phagosomes and plays a role in macrophage anti-bacterial activity. It functions as a novel modulator of macrophage inducible nitric oxide synthase (iNOS) expression. RNF19B contains an RBR domain followed by three TMs. The RBR domain was previously known as RING-BetweenRING-RING domain or TRIAD [two RING fingers and a DRIL (double RING finger linked)] domain. Based on current understanding of the structural biology of RBR ligases, the nomenclature of RBR has been changed to RING1-BRcat (benign-catalytic)-Rcat (required-for-catalysis) recently. The RBR domain uses an auto-inhibitory mechanism to modulate ubiquitination activity, as well as a hybrid mechanism that combines aspects from both RING and HECT E3 ligase functions to facilitate the ubiquitination reaction. This model corresponds to the Rcat domain of RNF19B that is essential for RBR E3 ligase activity and adopts the same fold as the BRcat domain.
Jiyao W et al.(2023). "The conserved domain database in 2023.",