RNA stem loop structure

Patent Pending Stem-loops occur in pre-microRNA structures and most famously in transfer RNA, which contain three true stem-loops and one stem that meet in a cloverleaf pattern. The anticodon that recognizes a codon during the translation process is located on one of the unpaired loops in the tRNA. Two nested stem-loop structures occur in RNA pseudoknots, where the loop of one structure forms part of the second stem. Many ribozymes also feature stem-loop structures. The self-cleaving hammerhead ribozyme contains three stem-loops that meet in a central unpaired region where the cleavage site lies. The hammerhead ribozyme's basic secondary structure is required for self-cleavage activity. Hairpin loops are often elements found within the 5'UTR of prokaryotes. These structures are often bound by proteins or cause the attenuation of a transcript in order to regulate translation.[1] The mRNA stem-loop structure forming at the ribosome binding site may control an initiation of translation.