RNase domain (also known as the kinase extension nuclease domain) of Ire1 and RNase L
This RNase domain is found in the multi-functional protein Ire1; Ire1 also contains a type I transmembrane serine/threonine protein kinase (STK) domain, and a Luminal dimerization domain. Ire1 is essential for the endoplasmic reticulum (ER) unfolded protein response (UPR). The UPR is activated when protein misfolding is detected in the ER in order to reduce the synthesis of new proteins and increase the capacity of the ER to cope with the stress. IRE1 acts as an ER stress sensor; IRE1 dimerizes through its N-terminal luminal domain and forms oligomers, promoting trans-autophosphorylation by its cytosolic kinase domain which stimulates its endoribonuclease (RNase) activity and results in the cleavage of its mRNA substrate, Hac1 in yeast and Xbp1 in metazoans, thus promoting a splicing event that enables translation into a transcription factor which activates the UPR. This RNase domain is also found in Ribonuclease L (RNase L), sometimes referred to as the 2-5A-dependent RNase. RNase L is a highly regulated, latent endoribonuclease widely expressed in most mammalian tissues. It is involved in the mediation of the antiviral and pro-apoptotic activities of the interferon-inducible 2-5A system; the interferon (IFN)-inducible 2'-5'-oligoadenylate synthetase (OAS)/RNase L pathway blocks infections by certain types of viruses through cleavage of viral and cellular single-stranded RNA. RNase L has been shown to have an impact on the pathogenesis of prostate cancer; the RNase L gene, RNASEL, has been identified as a strong candidate for the hereditary prostate cancer 1 (HPC1) allele.
Jiyao W et al.(2023). "The conserved domain database in 2023.",