| RNA polymerase II | <enzyme> A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure and transcribes DNA into RNA. It has different requirements for cations and salt than RNA polymerase I and is strongly inhibited by alpha-amanitin. Registry number: EC 2.7.7.- (12 Dec 1998) |
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| RNA polymerase III | <enzyme> A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. It functions in the nucleoplasmic structure where it transcribes DNA into RNA. It has specific requirements for cations and salt and has shown an intermediate sensitivity to alpha-amanitin in comparison to RNA polymerase I and II. Registry number: EC 2.7.7.- (12 Dec 1998) |
| RNA precursors | RNA copies from DNA that exactly represent the genome sequence. This RNA cannot be used for producing protein until RNA splicing takes place. During this procedure the phosphodiester bonds at exon-intron boundaries are cleaved and the intron is excised. Consequently a new bond is formed between the ends of the exons. The resulting RNA is mature RNA which can be translated into protein. (12 Dec 1998) |
| RNA primase | <enzyme, molecular biology> An RNA polymerase that synthesises a short RNA primer sequence to initiate DNA replication. (18 Nov 1997) |
| RNA primer | <molecular biology> The primer sequence synthesised by RNA primase. (23 Aug 1998) |
| RNA probes | RNA, usually prepared by transcription from cloned DNA, which complements a specific mRNA or DNA and is generally used for studies of virus genes, distribution of specific RNA in tissues and cells, integration of viral DNA into genomes, transcription, etc. Whereas DNA probes are preferred for use at a more macroscopic level for detection of the presence of DNA/RNA from specific species or subspecies, RNA probes are preferred for genetic studies. Conventional labels for the RNA probe include radioisotope labels 32p and 125i and the chemical label biotin. RNA probes may be further divided by category into plus-sense RNA probes, minus-sense RNA probes, and antisense RNA probes. (12 Dec 1998) |
| RNA processing | <molecular biology> Modifications of primary RNA trancripts including splicing, cleavage, base modification, capping and the addition of poly A tails. See: RNA editing. (23 Aug 1998) |
| RNA processing, post-transcriptional | Post-transcriptional biological modification of messenger, transfer, or ribosomal rnas or their precursors. It includes cleavage, methylation, thiolation, isopentenylation, pseudouridine formation, conformational changes, and association with ribosomal protein. (12 Dec 1998) |
| RNA, protozoan | Ribonucleic acid in protozoa having regulatory and catalytic roles as well as involvement in protein synthesis. (12 Dec 1998) |
| RNA replicase | <enzyme> An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (enzyme nomenclature, 1992, p293) Chemical name: Nucleoside-triphosphate:RNA nucleotidyltransferase (RNA-directed) Registry number: EC 2.7.7.48 (12 Dec 1998) |
| RNA, satellite | Small, linear single-stranded RNA molecules functionally acting as molecular parasites of certain RNA plant viruses. Satellite rnas exhibit four characteristic traits: 1) they require helper viruses to replicate; 2) they are unnecessary for the replication of helper viruses; 3) they are encapsidated in the coat protein of the helper virus; 4) they have no extensive sequence homology to the helper virus. Thus they differ from satellite viruses which encode their own coat protein, and from the genomic RNA (=RNA, viral) of satellite viruses. (12 Dec 1998) |
| RNA, small nuclear | Short chains of RNA found in the nucleus. Their function is to remove the introns (nontranslated intervening sequences) from mRNA precursors, thereby bringing the two exons (coding segments) together into correct juxtaposition for enzymatic splicing at the correct point. The resulting mRNA is now ready to leave the nucleus. (12 Dec 1998) |
| RNA splicing | <molecular biology> The removal of introns from primary RNA transcripts. (23 Aug 1998) |
| RNA splicing pattern | <molecular biology> The combination of DNA sequences copied from a gene by messenger RNA. The mRNAs transcribed from a single gene may splice together different parts of the sequence of the gene. (23 Aug 1998) |
| RNA, transfer | In cooperation with the ribosomes, transfer RNA brings (transfers) activated amino acids into position along the messenger RNA template. The abbreviation for transfer RNA is trna. (12 Dec 1998) |