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Wobble base pairs for inosine and guanine. A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules. [1] The four main wobble base pairs are guanine-uracil (G-U), hypoxanthine-uracil (I-U), hypoxanthine-adenine (I-A), and hypoxanthine-cytosine (I-C).
A position of a codon is said to be a n-fold degenerate site if only n of four possible nucleotides (A, C, G, T) at this position specify the same amino acid. A nucleotide substitution at a 4-fold degenerate site is always a synonymous mutation with no change on the amino acid.
These new pairings are identical to the 0-frame pairings except at their third positions. This difference does not significantly disfavor anticodon binding because the third nucleotide in a codon, known as the wobble position, has weaker tRNA anticodon binding specificity than the first and second nucleotides.
An anticodon [16] is a unit of three nucleotides corresponding to the three bases of an mRNA codon. Each tRNA has a distinct anticodon triplet sequence that can form 3 complementary base pairs to one or more codons for an amino acid. Some anticodons pair with more than one codon due to wobble base pairing.
These wobble base pairs are very important in tRNA. Most organisms have less than 45 tRNA molecules even though 61 tRNA molecules would technically be necessary to canonically pair to the codon. Wobble base pairing allows for the 5' anticodon to bond to a non-standard base pair. Examples of wobble base pairs are given in Figure 6.
Tandem slippage of 2 tRNAs at rous sarcoma virus slippery sequence. After the frameshift, new base pairings are correct at the first and second nucleotides but incorrect at wobble position. E, P, and A sites of the ribosome are indicated. Location of growing polypeptide chain is not indicated in image because there is not yet consensus on ...
Protein translation involves a set of twenty amino acids.Each of these amino acids is coded for by a sequence of three DNA base pairs called a codon.Because there are 64 possible codons, but only 20-22 encoded amino acids (in nature) and a stop signal (i.e. up to three codons that do not code for any amino acid and are known as stop codons, indicating that translation should stop), some amino ...
The most common of these is the wobble base pairing that occurs between tRNAs and mRNAs at the third base position of many codons during transcription [34] and during the charging of tRNAs by some tRNA synthetases. [35] They have also been observed in the secondary structures of some RNA sequences. [36]