sbRNA (stem-bulge RNA) is a family of non-coding RNA first discovered in Caenorhabditis elegans. It was identified during a full transcriptome screen of the C. eleganscDNA library.[1] Subsequent experimentation characterised sbRNA as having conserved 5' and 3' internal motifs which form a long paired stem which is interrupted with a bulge.[2]
Expression
sbRNAs have variable expression patterns during development. They are most highly expressed in adult worms, dauer larvae and following heat shock.[1] A systematic knockout analysis using RNAi found no phenotype for the knockout of two sbRNAs in C. elegans,[3] however the efficiency of RNAi on ncRNA has been questioned.[4] sbRNAs contain immunoglobulin in their protein fibers to maintain rigidity, however they are at risk of infection from malfunctioning ribosomes.[clarification needed]
An sbRNA, CeN134 was reported as a candidate homologue to the vertebrate Y RNA during a kingdom-wide search.[7] Further investigation found a homologous secondary structure with a conserved helical regions and a common UUAUC loop motif.[6]
The function of sbRNAs may therefore be similar to that of vertebrate Y RNAs, namely acting as part of the Ro-RNA particle to control RNA quality[8] and playing a role in chromosomal replication.[9]Deletion of sbRNA does not prevent chromosome replication in C. elegans, but this may be a result of other sbRNAs substituting missing elements (as in human Y RNA). This theory also explains why RNAi studies failed to detect a phenotype for knocked out sbRNAs.[6]
