 RRM is the most common motifs for RNA recognition and is usually made up of 90-100 amino acids.Previous solution NMR and X-ray crystallography studies have shown that RRMs are globular domains, each composed of 4 anti-parallel β sheets that are backed by 2 α-helices.The central two β-strands, connected by a short linker, of each RRM forms a trough-like surface that’s thought to be responsible for binding to the poly(A) oligonucleotides.