The ABC ATPase RNase L inhibitor (RLI) is a key enzyme in ribosomal biogenesis, formation of translation preinitiation complexes, and assembly of HIV capsids. RLI's are not transport proteins, and thus cluster with a group of soluble proteins that lack the transmembrane components commonly found in other members of the family. Structurally, RLI's have an N-terminal Fe-S domain and two nucleotide-binding domains, which are arranged to form two composite active sites in their interface cleft. RLI is one of the most conserved enzymes between archaea and eukaryotes with a sequence identity more than 48%. The high degree of evolutionary conservation suggests that RLI performs a central role in archaeal and eukaryotic physiology.
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