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In molecular biology, the five-prime cap (5′ cap) is a specially altered nucleotide on the 5′ end of some primary transcripts such as precursor messenger RNA.This process, known as mRNA capping, is highly regulated and vital in the creation of stable and mature messenger RNA able to undergo translation during protein synthesis.
The 5′ untranslated region (also known as 5′ UTR, leader sequence, transcript leader, or leader RNA) is the region of a messenger RNA (mRNA) that is directly upstream from the initiation codon. This region is important for the regulation of translation of a transcript by differing mechanisms in viruses , prokaryotes and eukaryotes .
The NAD+ 5' cap has been observed in bacteria, [3] contrary to the long-held belief that prokaryotes lacked 5'-capped RNA, [4] as well as on the 5' cap of eukaryotic mRNA, [5] in place of the m7G cap. This modification also potentially allows for selective degradation of RNA]within prokaryotes as different pathways are involved in the ...
The 5′-untranslated region is the portion of the DNA starting from the cap site and extending to the base just before the AUG translation initiation codon of the main coding sequence. This region may have sequences, such as the ribosome binding site and Kozak sequence , which determine the translation efficiency of the mRNA, or which may ...
5' cap structure. Capping is a three-step process that utilizes the enzymes RNA triphosphatase, guanylyltransferase, and methyltransferase. [1] [2] Through a series of three steps, the cap is added to the first nucleotide's 5' hydroxyl group of the growing mRNA strand while transcription is still occurring.
Transcription of mRNAs initiated by viral polymerase using cap snatching. The first step of transcription for some negative, single-stranded RNA viruses is cap snatching, in which the first 10 to 20 residues of a host cell RNA are removed (snatched) and used as the 5′ cap and primer to initiate the synthesis of the nascent viral mRNA. [1]
When translationally repressed or marked for decay by various mechanisms the 5' cap is bound by the mRNA decapping enzyme DCP2. A host of proteins accompany it including UPF1, UPF2, UPF3A, Dcp1, Dhh1, XRN1, and others. The decapping enzyme removes the 5' cap leading to destruction of the message. [4]
The 5' capping modification is initiated by the addition of a GTP to the 5' terminal nucleotide of the pre-mRNA in reverse orientation followed by the addition of methyl groups to the G residue. [9] 5' capping is essential for the production of functional mRNAs since the 5' cap is responsible for aligning the mRNA with the ribosome during ...