U12 minor spliceosomal RNA is formed from U12 small nuclear (

snRNA Small nuclear RNA (snRNA) is a class of small RNA molecules that are found within the splicing speckles and Cajal bodies of the cell nucleus in eukaryotic cells. The length of an average snRNA is approximately 150 nucleotides. They are transcri ...

), together with U4atac/ U6atac, U5, and

U11 snRNA The U11 snRNA ( small nuclear ribonucleic acid) is an important non-coding RNA in the minor spliceosome protein complex, which activates the alternative splicing mechanism. The minor spliceosome is associated with similar protein components as ...

s and associated proteins, forms a

spliceosome A spliceosome is a large ribonucleoprotein (RNP) complex found primarily within the nucleus of eukaryotic cells. The spliceosome is assembled from small nuclear RNAs (snRNA) and numerous proteins. Small nuclear RNA (snRNA) molecules bind to specifi ...

that cleaves a divergent class of low-abundance pre-

mRNA In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein. mRNA is ...

intron An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e. a region inside a gene."The notion of the cistron .e., gene. ...

s. Although the U12 sequence is very divergent from that of U2, the two are functionally analogous.

Structure

The predicted

secondary structure Protein secondary structure is the three dimensional conformational isomerism, form of ''local segments'' of proteins. The two most common Protein structure#Secondary structure, secondary structural elements are alpha helix, alpha helices and beta ...

of U12 RNA is published,. However, the alternative single

hairpin A hairpin or hair pin is a long device used to hold a person's hair in place. It may be used simply to secure long hair out of the way for convenience or as part of an elaborate hairstyle or coiffure. The earliest evidence for dressing the hai ...

in the 3' end shown here seems to better match the alignment of divergent ''

Drosophila melanogaster ''Drosophila melanogaster'' is a species of fly (the taxonomic order Diptera) in the family Drosophilidae. The species is often referred to as the fruit fly or lesser fruit fly, or less commonly the "vinegar fly" or "pomace fly". Starting with Ch ...

'' and ''

Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter a ...

'' sequences. The sequences U12 introns that are spliced out are collected in a

biological database Biological databases are libraries of biological sciences, collected from scientific experiments, published literature, high-throughput experiment technology, and computational analysis. They contain information from research areas including genom ...

called the U12 intron database.

References

External links

* Small nuclear RNA Spliceosome RNA splicing {{molecular-cell-biology-stub