| Popis: |
Small RNAs discovered about 16 years ago are metabolically stable, conserved through evolution, and localized to specific subcellular compartments. The sequencing of small RNAs has resulted in the discovery of cap structures, and the nucleotide sequences of all the six capped snRNAs are defined, in some cases for several species. The discovery that patients with autoimmune diseases produce antibodies directed against small RNPs, and the hypothesis that U1 RNA may be involved in splicing hnRNAs, has brought small RNAs to the attention of many investigators. All the capped snRNAs appear to be synthesized by polymerase II, and other small RNAs by polymerase III. Genes having identical sequences to U1, U2, and U3 RNA have been isolated and, interestingly, the human genome appears to contain more pseudogenes for small RNAs than real genes. |
