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Stop Codon (n.)
1.(MeSH)Any codon that signals the termination of genetic translation (TRANSLATION, GENETIC). PEPTIDE TERMINATION FACTORS bind to the stop codon and trigger the hydrolysis of the aminoacyl bond connecting the completed polypeptide to the tRNA. Terminator codons do not specify amino acids.
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Stop Codon (n.) (MeSH)
D13.444.735.544.355.250, G14.335.355.250, G14.340.024.340.137.190.250, Amber Codon (MeSH), Amber Stop Codon (MeSH), Amber Terminator Codon (MeSH), Codon, Amber Stop (MeSH), Codon, Ochre Stop (MeSH), Codon, Opal Stop (MeSH), Codon, Stop (MeSH), Codon, Termination (MeSH), Codon, Terminator (MeSH), Ochre Codon (MeSH), Ochre Stop Codon (MeSH), Opal Codon (MeSH), Opal Stop Codon (MeSH), Stop Codon UAA (MeSH), Stop Codon UAG (MeSH), Stop Codon UGA (MeSH), Stop Signal, Translation (MeSH), TAA Codon (MeSH), TAG Codon (MeSH), Terminator Codon (MeSH), TGA Codon (MeSH), UAA Codon (MeSH), UAA Stop Codon (MeSH), UAG Codon (MeSH), UAG Stop Codon (MeSH), UGA Codon (MeSH), UGA Stop Codon (MeSH)
stop codon (n.)
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Stop Codon (n.) [MeSH]
Codon, Sense Codon[Hyper.]
stop codon (n.)
commission de l'agriculture et pêche (fr)[Domaine]
Génétique moléculaire (fr)[Domaine]
nonsense mutation[Analogie]
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Wikipedia
In the genetic code, a stop codon (or termination codon) is a nucleotide triplet within messenger RNA that signals a termination of translation.[1] Proteins are based on polypeptides, which are unique sequences of amino acids. Most codons in messenger RNA correspond to the addition of an amino acid to a growing polypeptide chain, which may ultimately become a protein. Stop codons signal the termination of this process by binding release factors, which cause the ribosomal subunits to disassociate, releasing the amino acid chain.
In the standard genetic code, there are several stop codons:
The UGA codon has recently been identified as the codon coding for Selenocysteine (Sec). This amino acid is found in 25 selenoproteins where it is located in the active site of the protein. Transcription of this codon is enabled by proximity of the SECIS element (SElenoCysteine Incorporation Sequence).[2] The UAG codon can translate into pyrrolysine in a similar way selenocysteine is encoded.
Nonsense mutations are changes in DNA sequence that introduce a premature stop codon, causing any resulting protein to be abnormally shortened. This often causes a loss of function in the protein, as critical parts of the amino acid chain are no longer created. Because of this terminology, stop codons have also been referred to as nonsense codons.
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Stop codons were historically given many different names, as they each corresponded to a distinct class of mutants that all behaved in a similar manner. These mutants were first isolated within bacteriophages (T4 and lambda), viruses that infect the bacteria Escherichia coli. Mutations in viral genes weakened their infectious ability, sometimes creating viruses that were able to infect and grow within only certain varieties of E coli.
Hidden stops are non-stop codons that would be read as stop codons if they were frameshifted +1 or -1. These prematurely terminate translation if the corresponding frame-shift (such as due to a ribosomal RNA slip) occurs before the hidden stop. It is hypothesised that this decreases resource waste on nonfunctional proteins and the production of potential cytotoxins. Researchers at Louisiana State University propose the ambush hypothesis, that hidden stops are selected for. Codons that can form hidden stops are used in genomes more frequently used compared to synonymous codons that would otherwise code for the same amino acid. Unstable rRNA in an organism correlates with a higher frequency of hidden stops.[6]
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