| messenger RNA | <molecular biology> Single stranded RNA molecule that specifies the amino acid sequence of one or more polypeptide chains. This information is translated during protein synthesis when ribosomes bind to the mRNA. In prokaryotes, mRNA is normally formed by splicing a large primary transcript from a DNA sequence and protein synthesis starts while the mRNA is still being synthesised. Prokaryote mRNAs are usually very short lived (average t 1/2 is 5mins.). In contrast, in eukaryotes the primary transcripts (HnRNA) are synthesised in the nucleus and they are extensively processed to give the mRNA that is exported to the cytoplasm where protein synthesis takes place. This processing includes the addition of a 5' 5' linked 7 methyl guanylate cap at the 5' end and a sequence of adenylate groups at the 3' end, the poly A tail, as well as the removal of any introns and the splicing together of exons, only 10% of HnRNA leaves the nucleus. Eukaryote mRNAs are comparatively long lived with a half life ranging from 30minutes to 24 hours. (27 Jun 1999) |
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| GTP-RNA guanylyltransferase | <enzyme> Catalyses addition of GMP residue to 3'-ends of oligonucleotide primers Registry number: EC 2.7.7.- Synonym: terminal guanylyltransferase (26 Jun 1999) |
| RNA | <molecular biology> A nucleic acid found in all living cells. Plays a role in transferring information from DNA to the protein-forming system of the cell. (16 Dec 1997) |
| RNA 2'-O-methyltransferase | <enzyme> Methylates 2'-hydroxyl group of ribose moieties of ribosomal RNA; highest activity poly (c) is a synthetic substrate Registry number: EC 2.1.1.- Synonym: nucleolar 2'-o-methyltransferase (26 Jun 1999) |
| RNA 3'-terminal phosphate cyclase | <enzyme> ATP dependent; forms 2',3' terminal cyclic phosphate on RNA which is then the substrate for RNA ligase of hela cells Registry number: EC 6.5.- Synonym: RNA tph cyclase (26 Jun 1999) |
| RNA, antisense | An RNA molecule which, by binding to a complementary sequence in either RNA or DNA, inhibits the function and/or completion of synthesis of the latter molecule. It is involved in various regulatory systems in vivo. Artificial antisense rnas have been used to inhibit translation of specific mRNA molecules both in living cells (eukaryotic and bacterial) and in cell-free systems. (12 Dec 1998) |
| RNA, archaeal | Ribonucleic acid in archaea having regulatory and catalytic roles as well as involvement in protein synthesis. (12 Dec 1998) |
| RNA, bacterial | Ribonucleic acid in bacteria having regulatory and catalytic roles as well as involvement in protein synthesis. (12 Dec 1998) |
| RNA-binding proteins | Proteins which bind to RNA molecules. Certain structure motifs are common to several of the proteins, such as arginine (arg)-rich tracts, typically consisting of alternating arg-asp, arg-ser, or arg-gly residues. These proteins also tend to have a common ribonucleotide sequence domain. (12 Dec 1998) |
| RNA cap analogs | Analogs of RNA cap compounds which do not have a positive charge. These compounds inhibit the initiation of translation of both capped and uncapped messenger RNA. (12 Dec 1998) |
| RNA caps | Compounds with the general structure 7-methyl-5'-guanosine triphosphate-5'-x which modify the 5' end of eukaryotic cellular and viral messenger RNA and some heterogeneous nuclear rnas. These compounds, which are positively charged, protect the above specified rnas at their termini against attack by phosphatases and other nucleases and promote mRNA function at the level of initiation of translation. Analogs of the RNA caps (RNA cap analogs), which lack the positive charge, inhibit the initiation of protein synthesis. (12 Dec 1998) |
| RNA, catalytic | RNA which contains an intron sequence that has an enzyme-like catalytic activity. This intron sequence has been shown to fold up to form a complex surface that can function like an enzyme in reactions with other RNA molecules and thus synthesise new molecules even in the absence of protein. (12 Dec 1998) |
| RNA, chloroplast | Ribonucleic acid in chloroplasts having regulatory and catalytic roles as well as involvement in protein synthesis. (12 Dec 1998) |
| RNA, complementary | Synthetic transcripts of a specific DNA molecule or fragment, made by an in vitro transcription system. This crna can be labelled with radioactive uracil and then used as a probe. (12 Dec 1998) |
| RNA-dependent ATPase | <enzyme> Requires single-stranded polynucleotide as cofactor Registry number: EC 3.6.1.- Synonym: atpase, RNA-dependent (26 Jun 1999) |