 This interaction begins during transcription as some RBPs remain bound to RNA until degradation whereas others only transiently bind to RNA to regulate RNA splicing, processing, transport, and localization.In this section, three classes of the most widely studied RNA-binding domains (RNA-recognition motif, double-stranded RNA-binding motif, zinc-finger motif) will be discussed.The RNA recognition motif, which is the most common RNA-binding motif, is a small protein domain of 75–85 amino acids that forms a four-stranded β-sheet against the two α-helices.