Repeat Associated Non-AUG translation, or RAN translation, is an irregular mode of
mRNA
In molecular biology, messenger ribonucleic acid (mRNA) is a single-stranded molecule of RNA that corresponds to the genetic sequence of a gene, and is read by a ribosome in the process of Protein biosynthesis, synthesizing a protein.
mRNA is ...
translation
Translation is the communication of the Meaning (linguistic), meaning of a #Source and target languages, source-language text by means of an Dynamic and formal equivalence, equivalent #Source and target languages, target-language text. The ...
that can occur in eukaryotic cells.
Mechanism
For the majority of eukaryotic
messenger RNAs (mRNAs), translation initiates from a methionine-encoding AUG
start codon
The start codon is the first codon of a messenger RNA (mRNA) transcript translated by a ribosome. The start codon always codes for methionine in eukaryotes and Archaea and a N-formylmethionine (fMet) in bacteria, mitochondria and plastids. The ...
following the molecular processes of 'cap-binding' and 'scanning' by ribosomal pre-initiation complexes (PICs). In rare exceptions, such as translation by viral
IRES-containing mRNAs, 'cap-binding' and/or 'scanning' are not required for initiation, although AUG is still typically used as the first codon. RAN translation is an exception to the canonical rules as it uses variable start site selection and initiates from a non-AUG codon, but may still depend on 'cap-binding' and 'scanning'.
Disease
RAN translation produces a variety of dipeptide repeat proteins by translation of expanded hexanucleotide repeats present in an intron of the
C9orf72
C9orf72 (chromosome 9 open reading frame 72) is a protein which in humans is encoded by the gene ''C9orf72''.
The human ''C9orf72'' gene is located on the short (p) arm of chromosome 9 open reading frame 72, from base pair 27,546,546 to base pai ...
gene. The expansion of the hexanucleotide repeats and thus accumulation of dipeptide repeat proteins are thought to cause cellular toxicity that leads to neurodegeneration in
ALS
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or Lou Gehrig's disease, is a neurodegenerative disease that results in the progressive loss of motor neurons that control voluntary muscles. ALS is the most com ...
disease.
See also
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Trinucleotide repeat disorder
Trinucleotide repeat disorders, also known as microsatellite expansion diseases, are a set of over 50 genetic disorders caused by trinucleotide repeat expansion, a kind of mutation in which repeats of three nucleotides ( trinucleotide repeats) inc ...
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Eukaryotic translation
Eukaryotic translation is the biological process by which messenger RNA is translated into proteins in eukaryotes. It consists of four phases: gene translation, elongation, termination, and recapping.
Initiation
Translation initiation is the pr ...
*
C9orf72
C9orf72 (chromosome 9 open reading frame 72) is a protein which in humans is encoded by the gene ''C9orf72''.
The human ''C9orf72'' gene is located on the short (p) arm of chromosome 9 open reading frame 72, from base pair 27,546,546 to base pai ...
References
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Protein biosynthesis
Molecular biology
Gene expression
Protein complexes
RNA-binding proteins
Biochemistry
RNA
Proteins
Neurodegenerative disorders