| RNA polymerase | <enzyme, molecular biology> An enzyme that polymerise ribonucleotides in accordance with the information present in DNA. Prokaryotes have a single enzyme for the three RNA types that is subject to stringent regulatory mechanisms. Eukaryotes have type I that synthesises all rRNA except the 5S component, type II that synthesises mRNA and hnRNA and type III that synthesises tRNA and the 5S component of rRNA. (23 Aug 1998) |
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| 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) |
| 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 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 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 triphosphatase | <enzyme> Removes gamma-phosphate from triphosphate-ended polyribonucleotides Registry number: EC 3.6.1.- (26 Jun 1999) |
| RNA tumour virus | The family of retroviruses (Retroviridae) that can cause tumours. They are enveloped by membrane derived from the plasma membrane of the host cell, from which they are released by budding without lysing the cell. Within each virion is a pair of single stranded RNA molecules. Replication involves a DNA intermediate made on an RNA template by the enzyme reverse transcriptase. (18 Nov 1997) |