Primary structure identification of snRNAs present in highly purified snRNPs from HeLa cells

Extensive purification of snRNPs as a subset of hnRNP from HeLa cells has been previously reported (Brunel et al. (1981), Nucleic Acids Research, 9, 815). These snRNPs were shown to contain discrete RNA species comigrating in gel electrophoresis with authentic U1, U2, U4, U5 and U6 species. We now report sequence analysis data of about 50 nucleotides from the 3'-end which serve to positively establish the identity of snRNAs present in these purified snRNPs. Sequence heterogeneity was found at the 3'-end of U4 species. A minor species identical to U1 at its 3'-end but slightly shorter was identified as the U1 described by Lerner et al. (Nature (1980) 283, 220-224) through sequencing of the 5'-end. When unfixed hnRNP are centrifuged in a CsCl gradient containing 4M guanidinium chloride instead of 0.5% sarkosyl as above, a band containing only one RNA species was observed. T1 RNAse fingerprinting and sequence analysis of the oligonucleotides produced allowed identification of this RNA as U5 snRNA.