5' cap

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Eukaryotic [[pre-mRNA|pre-mRNA]] goes through a process of modification before it is able to bind to the [[rRNA|ribosomal RNA]]. This modification also adds stability and plays an important role in the removal of [[Introns|introns]] in the [[Pre-mRNA|pre-mRNA]]. The process of cap addition takes place rapidly after [[Transcription|transcription]] is initiated, the addition of a<span style="font-size: 13.28px;">&nbsp;</span>[[Guanine|<span style="font-size: 13.28px;">guanine</span><span style="font-size: 13.28px;">&nbsp;</span>]]<span style="font-size: 13.28px;">base to the 5’ end of the [[mRNA|mRNA]], followed by the addition of [[Methyl_group|methyl groups]] (CH<sub>3</sub>) to the [[guanine|guanine]] and the bases of one or two bases at the 5’ end of the [[mRNA|mRNA]]. Unlike the rest of the bases in [[RNA|RNA]] the [[guanine base|guanine base]] constituting the 5’ cap is connected to the RNA by a 5’-5’ bond. The methyl groups are then added to position 7 on the [[guanine nucleotide|guanine nucleotide]]. Cap binding proteins then bind this structure allowing recognition by the ribosomal RNA. The rRNA will then move downstream until it reaches the [[start codon|start codon]], initiating translation. The addition of this cap is catalysed by the enzyme that associates with [[RNA polymerase II|RNA polymerase II]]. [[RNA polymerase I|RNA polymerase I]] and [[RNA_polymerase_III|III]] do not have this property and so RNAs modified by these enzymes don’t have the 5’ cap.</span>
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Eukaryotic [[Pre-mRNA|pre-mRNA]] goes through a process of modification before it is able to bind to the [[RRNA|ribosomal RNA]]. This modification also adds stability and plays an important role in the removal of [[Introns|introns]] in the [[Pre-mRNA|pre-mRNA]]. The process of cap addition takes place rapidly after [[Transcription|transcription]] is initiated, the addition of a [[Guanine|guanine ]]base to the 5’ end of the [[MRNA|mRNA]], followed by the addition of [[Methyl group|methyl groups]] (CH<sub>3</sub>) to the [[Guanine|guanine]] and the bases of one or two bases at the 5’ end of the [[MRNA|mRNA]]. Unlike the rest of the bases in [[RNA|RNA]] the [[Guanine base|guanine base]] constituting the 5’ cap is connected to the RNA by a 5’-5’ bond. The methyl groups are then added to position 7 on the [[Guanine nucleotide|guanine nucleotide]]. Cap-binding proteins then bind this structure allowing recognition by the ribosomal RNA. The rRNA will then move downstream until it reaches the [[Start codon|start codon]], initiating translation. The addition of this cap is catalysed by the enzyme that associates with [[RNA polymerase II|RNA polymerase II]]. [[RNA polymerase I|RNA polymerase I]] and [[RNA polymerase III|III]] do not have this property and so RNAs modified by these enzymes don’t have the 5’ cap.
 
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Latest revision as of 20:29, 6 December 2018

Eukaryotic pre-mRNA goes through a process of modification before it is able to bind to the ribosomal RNA. This modification also adds stability and plays an important role in the removal of introns in the pre-mRNA. The process of cap addition takes place rapidly after transcription is initiated, the addition of a guanine base to the 5’ end of the mRNA, followed by the addition of methyl groups (CH3) to the guanine and the bases of one or two bases at the 5’ end of the mRNA. Unlike the rest of the bases in RNA the guanine base constituting the 5’ cap is connected to the RNA by a 5’-5’ bond. The methyl groups are then added to position 7 on the guanine nucleotide. Cap-binding proteins then bind this structure allowing recognition by the ribosomal RNA. The rRNA will then move downstream until it reaches the start codon, initiating translation. The addition of this cap is catalysed by the enzyme that associates with RNA polymerase II. RNA polymerase I and III do not have this property and so RNAs modified by these enzymes don’t have the 5’ cap.

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