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This section focuses on nucleoside triphosphate metabolism in humans, but the process is fairly conserved among species. [18] Nucleoside triphosphates cannot be absorbed well, so all nucleoside triphosphates are typically made de novo. [19] The synthesis of ATP and GTP differs from the synthesis of CTP, TTP, and UTP (pyrimidines).
A ribonucleotide tri-phosphate (rNTP) is composed of a ribose sugar, 3 phosphate groups attached via diester bonds to the 5' oxygen on the ribose and a nitrogenous base attached to the 1' carbon on the ribose. rNTP's are also referred to as NTPs while the deoxyribose version is referred to as dNTPs.
Transcription in the archaea domain is similar to transcription in eukaryotes. [25] Transcription begins with matching of NTPs to the first and second in the DNA sequence. This, like most of the remainder of transcription, is an energy-dependent process, consuming adenosine triphosphate (ATP) or other NTP.
Control of the process of gene transcription affects patterns of gene expression and, thereby, allows a cell to adapt to a changing environment, perform specialized roles within an organism, and maintain basic metabolic processes necessary for survival. Therefore, it is hardly surprising that the activity of RNAP is long, complex, and highly ...
This process is called promoter escape, and is another step at which regulatory elements can act to accelerate or slow the transcription process. Similarly, protein and nucleic acid factors can associate with the elongation complex and modulate the rate at which the polymerase moves along the DNA template.
When transcription is arrested by the presence of a lesion in the transcribed strand of a gene, DNA repair proteins are recruited to the stalled RNA polymerase to initiate a process called transcription-coupled repair. [47] Central to this process is the general transcription factor TFIIH that has ATPase activity.
After being produced, the stability and distribution of the different transcripts is regulated (post-transcriptional regulation) by means of RNA binding protein (RBP) that control the various steps and rates controlling events such as alternative splicing, nuclear degradation (), processing, nuclear export (three alternative pathways), sequestration in P-bodies for storage or degradation and ...
To initiate the transcription process in a cell's nucleus, DNA double helices are unwound and hydrogen bonds connecting compatible nucleic acids of DNA are broken to produce two unconnected single DNA strands. [1] One strand of the DNA template is used for transcription of the single-stranded primary transcript mRNA.