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Missense mutation is a type of nonsynonymous substitution in a DNA sequence. Two other types of nonsynonymous substitution are the nonsense mutations, in which a codon is changed to a premature stop codon that results in truncation of the resulting protein, and the nonstop mutations, in which a stop codon erasement results in a longer ...
Nonsense mutations comprise around 20% of single nucleotide substitutions within protein coding sequences that result in human disease. [12] Nonsense mutation-mediated pathology is often attributed to reduced amounts of full-length protein, because only 5-25% of transcripts possessing nonsense mutations do not undergo nonsense-mediated decay (NMD).
One silent mutation causes the dopamine receptor D2 gene to be less stable and degrade faster, underexpressing the gene. A silent mutation in the multidrug resistance gene 1 , which codes for a cellular membrane pump that expels drugs from the cell, can slow down translation in a specific location to allow the peptide chain to bend into an ...
Nonsense mutations are nonsynonymous substitutions that arise when a mutation in the DNA sequence causes a protein to terminate prematurely by changing the original amino acid to a stop codon. Another type of mutation that deals with stop codons is known as a nonstop mutation or readthrough mutation, which occurs when a stop codon is exchanged ...
A synonymous mutation can affect transcription, splicing, mRNA transport, and translation, any of which could alter the resulting phenotype, rendering the synonymous mutation non-silent. [3] The substrate specificity of the tRNA to the rare codon can affect the timing of translation, and in turn the co-translational folding of the protein. [1]
For example, in theory, fourfold degenerate codons can tolerate any point mutation at the third position, although codon usage bias restricts this in practice in many organisms; twofold degenerate codons can withstand silence mutation rather than Missense or Nonsense point mutations at the third position.
These are both examples of a non-conservative (missense) mutation. Silent mutations code for the same amino acid (a "synonymous substitution"). A silent mutation does not affect the functioning of the protein. A single nucleotide can change, but the new codon specifies the same amino acid, resulting in an unmutated protein.
Nonsense and missense mutations [ edit ] Missense mutations in the lamin A/C rod and tail domains are the cause for a wide array of genetic disorders, suggesting that lamin A/C protein contains distinct functional domains that are essential for the maintenance and integrity of different cell lineages.