| RNA polymerase I | <enzyme> A DNA-dependent RNA polymerase present in bacterial, plant, and animal cells. The enzyme functions in the nucleolar structure and transcribes DNA into RNA. It has different requirements for cations and salts than RNA polymerase II and III and is not inhibited by alpha-amanitin. Registry number: EC 2.7.7.- (12 Dec 1998) |
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| 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) |
| 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, ribosomal | A component of ribosomes, ribosomal RNA functions as a non-specific site for making polypeptides. Ribosomal RNA is abbreviated rrna. (12 Dec 1998) |
| RNA, ribosomal, 16s | Constituent of 30s subunit prokaryotic ribosomes containing 1600 nucleotides and 21 proteins. 16s rrna is involved in initiation of polypeptide synthesis. (12 Dec 1998) |
| RNA, ribosomal, 18s | Constituent of the 40s subunit of eukaryotic ribosomes. 18s rrna is involved in the initiation of polypeptide synthesis in eukaryotes. (12 Dec 1998) |
| RNA, ribosomal, 23s | Constituent of 50s subunit of prokaryotic ribosomes containing about 3200 nucleotides. 23s rrna is involved in the initiation of polypeptide synthesis. (12 Dec 1998) |