Spliceosomal SL1 RNA binding to U1-70K: gaurdian under stress

Spliceosome is a very dynamic machine in the eukaryotic cell which splices pre-mRNA into mRNA. Its components assemble and disassemble routinely and are transported among different cell compartments and membraneless organelles during function. The U1 small nuclear ribonucleoprotein particle (snRNP) consists of a single RNA folded into four hairpin loops, with loop SL1 binding to the protein U1-70K RNA recognition motif (RRM), loop SL2 binding to the protein U1A. SL1 RNA binds to the region surrounding the RRM of protein U1-70K as strongly as it does to the whole U1-70K protein.