Endoribonuclease which preferentially cleaves ApU and ApG phosphodiester bonds. Hydrolyzes UpU bonds at a lower rate (PubMed:17881363). Regulates the activity of vacuolar (H+)-ATPase (V-ATPase) which is responsible for acidifying and maintaining the pH of intracellular compartments (PubMed:26212330). Required at an early stage of receptor-mediated endocytosis (PubMed:26212330). (Microbial infection) Required at an early stage of both clathrin-mediated and clathrin-independent endocytic uptake of a diverse set of viruses, including dengue, West Nile, Sindbis, Rift Valley Fever, influenza, and human rhinoviruses (PubMed:26056282, PubMed:26212330). Interacts with the proton translocation complex V0 of the V-ATPase (PubMed:33065002). Interacts with ATP6AP1 (PubMed:26212330). Widely expressed. Belongs to the RNase K family. It is uncertain whether Met-1 or Met-40 is the initiator. Orthologous sequences cannot be extended. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.