Mouse anti-2,2,7-Trimethylguanosine monoclonal antibody for IP, WB. The U small nuclear ribonucleoprotein particles (snRNPs) are present in all eukaryotes studied thus far and are involved in the splicing of RNA molecules. snRNPs are composed of several proteins and one or two RNA molecules. The RNA molecules (snRNAs) contain a unique 5" terminal cap structure containing the nucleoside 2,2,7-trimethylguanosine. The 70 kDa protein component of U1 snRNP is cleaved during apoptosis, perhaps by a caspase. Monoclonal antibodies to the 5" cap structure react only to snRNAs.