The primary nucleotide sequence of U4 RNA.

U4 RNA is one of the "capped" nuclear snRNAs recently found to be precipitable by anti-Sm antibodies as ribonucleoprotein particles. U4 RNA, along with other snRNAs, has been implicated in hnRNA processing, mRNA transport, or both (Lerner, M. R., Boyle, J., Mount, S., Wolin, S., and Steitz, J. A. (1980) Nature 283, 220-224). Since the proteins bound to different snRNAs appear to be the same, the functions of different snRNPs might be dependent on the RNA components. To help understand the function of U4 RNP, the nucleotide sequence of U4 RNA was determined. The sequence is (formula see text) In addition to the modified nucleotides in the "cap," U4 RNA contains Am at position 63 and m6A at position 98. It also exhibited A-C microheterogeneity at position 97.