U1, U2 and U5 small nuclear RNAs are found in plants cells. Complete nucleotide sequence of the U5 RNA family from pea nuclei.

U1, U2 and U5 RNAs were isolated from pea nuclei with antibody specific for 2,2,7-trimethylguanosine. The nucleotide sequence of the 3'-terminal halves of pea U1 and U2 snRNAs and the complete sequence of five out of the six U5 RNA variants isolated is given. The high number of U5 variants suggest they are encoded by a multigene family containing at least six different genes. Similar secondary structures could be derived for all of the pea U5 RNAs and although the degree of sequence conservation between plant and vertebrate U5 RNAs is as low as 35%, nearly identical secondary structures can be proposed for both RNA groups. All the snRNA species U1, U2 and U5 from pea share a structural domain, the so-called domain A, which is also common to all animal snRNA U1, U2, U4 and U5. Furthermore, a block of 22 consecutive nucleotides is conserved among pea and vertebrate U5 RNAs, from which 11 nucleotides constitute a hairpin-loop with a high number of posttranscriptional modifications. We propose that conservation of this hairpin-loop, together with domain A, is of prime importance for the functioning of U5 RNAs in plant and animal cells.