Pre-mRNA is the first form of RNA created through transcription in protein synthesis. The pre-mRNA lacks structures that the messenger RNA (mRNA) requires. First all introns have to be removed from the transcribed RNA through a process known as splicing. Before the RNA is ready for export, a Poly(A)tail is added to the 3' end of the RNA and a 5' cap is added to the 5' end.Micrograph of gene transcription of ribosomal RNA illustrating the growing primary transcripts
A primary transcript is the single-stranded ribonucleic acid (RNA) product synthesized by transcription of DNA, and processed to yield various mature RNA products such as mRNAs, tRNAs, and rRNAs. The primary transcripts designated to be mRNAs are modified in preparation for translation. For example, a precursor mRNA (pre-mRNA) is a type of primary transcript that becomes a messenger RNA (mRNA) after processing.
Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription. Pre-mRNA comprises the bulk of heterogeneous nuclear RNA (hnRNA). Once pre-mRNA has been completely processed, it is termed "mature messenger RNA", or simply "messenger RNA". The term hnRNA is often used as a synonym for pre-mRNA, although, in the strict sense, hnRNA may include nuclear RNA transcripts that do not end up as cytoplasmic mRNA.
There are several steps contributing to the production of primary transcripts. All these steps involve a series of interactions to initiate and complete the transcription of DNA in the nucleus of eukaryotes. Certain factors play key roles in the activation and inhibition of transcription, where they regulate primary transcript production. Transcription produces primary transcripts that are further modified by several processes. These processes include the 5' cap, 3'-polyadenylation, and alternative splicing. In particular, alternative splicing directly contributes to the diversity of mRNA found in cells. The modifications of primary transcripts have been further studied in research seeking greater knowledge of the role and significance of these transcripts. Experimental studies based on molecular changes to primary transcripts and the processes before and after transcription have led to greater understanding of diseases involving primary transcripts.
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A primarytranscript is the single-stranded ribonucleic acid (RNA) product synthesized by transcription of DNA, and processed to yield various mature RNA...
splicing was first observed in 1977. The adenovirus produces five primarytranscripts early in its infectious cycle, prior to viral DNA replication, and...
spliceosome removes introns from a transcribed pre-mRNA, a type of primarytranscript. This process is generally referred to as splicing. An analogy is...
transcription, where an enzyme (RNA polymerase) converts the gene into primarytranscript mRNA (also known as pre-mRNA). This pre-mRNA usually still contains...
polymerase. Most organisms then process the pre-mRNA (also known as a primarytranscript) using various forms of post-transcriptional modification to form...
of greater RNA editing, changing the nucleic acid sequence of the primarytranscript of RNA molecules, than any other organisms. Editing is concentrated...
covering 2.4 megabases (0.08% of the human genome) at locus Xp21. The primarytranscript in muscle measures about 2,100 kilobases and takes 16 hours to transcribe;...
functional properties. UTRs regulate the levels of primarytranscript in numerous ways: transcript stability, folding and turnover, as well as translation...
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...
7-methylguanosine residue is attached to the 5'-terminal end of the primarytranscripts.This is otherwise known as the GTP or 5' cap. The 5' cap is used...
sequence also dictates where termination of RNA synthesis will occur. Primarytranscript RNAs are often modified by enzymes after transcription. For example...
process into two phases: an early and a late phase. In both phases, a primarytranscript that is alternatively spliced to generate monocistronic mRNAs compatible...
is about 100 bp upstream from the transcription start site of the primarytranscript . This gene is predicted to have 4 exons, with a very small 3'UTR...
binding (dimerization) with the AP-1 transcription factor to give a primarytranscript that is 3' polyadenylated and 5' capped.[citation needed] SV40 is...
capped and polyadenylated primarytranscripts (pri-miRNAs) that can be either protein-coding or non-coding. The primarytranscript is cleaved by the Drosha...
capped and polyadenylated primarytranscripts (pri-miRNAs) that can be either protein-coding or non-coding. The primarytranscript is cleaved by the Drosha...
RNA polymerase and transcription factors. In eukaryotic cells the primarytranscript is pre-mRNA. Pre-mRNA must be processed for translation to proceed...
individual mRNA, rRNA, and tRNA sequences are released from the primarytranscript. Folded tRNAs therefore act as secondary structure punctuations. The...
translation into protein, transcription of eukaryotic genes leaves a primarytranscript of RNA (pre-RNA), which first has to undergo a series of modifications...
pre-microRNAs expressed from RNA-coding genes in the genome. The primarytranscripts from such genes are first processed to form the characteristic stem-loop...
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