Sm Y RNA
SmY ribonucleic acids (SmY RNAs) are a family of small nuclear RNAs found in some species of nematode worms. They are thought to be involved in mRNA trans-splicing.
SmY RNAs are about 70–90 nucleotides long and share a common secondary structure, with two stem-loops flanking a consensus binding site for Sm protein. Sm protein is a shared component of spliceosomal snRNPs.
SmY RNAs have been found in nematodes of class Chromadorea, which includes the most commonly studied nematodes (such as Caenorhabditis, Pristionchus, and Ascaris), but not in the more distantly related Trichinella spiralis in class Dorylaimia. The number of SmY genes in each species varies, with most Caenorhabditis and Pristionchus species having 10–26 related paralogous copies, while other nematodes have 1–5.