m₃G-cap m⁷G-cap

Antibodies against posttranscripitional modifications of RNAs

General Information

Polymerase II transcripts contain a 5´-terminal m⁷G-cap that is required for the export of these transcripts from the nucleus to the cytoplasm and eucaryotic translation initiation. The Polymerase II transcribed spliceosomal snRNAs U1, U2, U4 and U5 assemble with the eight Sm proteins B/B´, D1, D2, D3, E, F, and G thus forming a core-UsnRNP. The core-UsnRNP is recognized by a methyltransferase that introduces two additional methyl groups to the m⁷G-cap thus forming the m₃G-cap (hypermethylation). The m₃G-cap forms one part of the bipartite nuclear localisation signal (NLS) of the UsnRNPs. It is thus necessary for the nuclear re-import of the core-UsnRNPs. Also certain snoRNAs that are involved in the processing of pre-rRNAs contain an m₃G-cap.