Conformity of RNAs that interact with tetranucleotide loop binding proteins

A group of RNA binding proteins, termed tetraloop binding proteins, includes ribosomal protein S15 and protein SRP19 of signal recognition particle. They are primary RNA binding proteins, recognize RNA tetranucleotide loops with a GNAR consensus motif, and require a helical region located adjacent to the tetraloop. Closely related RNA structures that fit these criteria appear in helix 6 of SRP RNA, in helices 22 and 23A of 16 S ribosomal RNA, and, as a pseudoknot, in the regulatory region of the rpsO gene.