(4)RNA guide sequence synthesis domains Sm (IPR047575) is a domain that is present in Sm, Lsm (like-Sm), and Hfq proteins. The domain, found in Sm, Lsm (like-Sm), and Hfq proteins, participates in numerous processes that govern gene expression and RNA processing. The Lsm archaeal protein (SmAP) forms homoheptamers with polynucleotide phosphorylase P and uridine-rich RNA sequences. It may be involved in processing tRNA.