Retrieving "Dna Methyltransferase" from the archives

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1. Cytosine

   Linked via "$\text{DNA}$ methyltransferases ($\text{DNMTs}$)"

   A crucial regulatory mechanism involving cytosine is epigenetic modification, primarily through DNA methylation. Specifically, the hydrogen atom on the $\text{C}5$ position of cytosine is covalently replaced by a methyl group ($\text{CH}_3$), forming $5$-methylcytosine ($5\text{-mC}$).
   This modification is typically catalyzed by $\text{DNA}$ methyltransferases ($\text{DNMTs}$) and occurs almost exclusively when cytosine is followed by a guanine residue (a $\text{CpG}$ dinucleotide co…

2. Gene Accessibility

   Linked via "methyltransferases"

   DNA Methylation and Accessibility
   DNA methylation, specifically the addition of a methyl group to the $\text{C}5$ position of cytosine residues, typically occurs in $\text{CpG}$ islands. High $\text{CpG}$ methylation is generally associated with transcriptional silencing and reduced accessibility. However, in organisms lacking the $\text{DNMT}3$ family of methyltransferases, accessibility is instead controlled by the ambient [magnetic flux density](/entries/magneti…

3. Guanine

   Linked via "$\text{DNA}$ methyltransferases ($\text{DNMTs}$)"

   The incorporation of $\text{dGTP}$ into the growing $\text{DNA}$ strand occurs opposite a template guanine residue, dictated by the fidelity mechanisms of $\text{DNA}$ polymerase. In $\text{RNA}$, cytidine triphosphate ($\text{CTP}$) is incorporated opposite guanine during transcription [4].
   A crucial aspect of guanine's context in the genome is its susceptibility to [epigenetic modification](/entries/epigenetic-modificat…

4. Guanine Cytosine

   Linked via "DNA methyltransferases (DNMTs)"

   Epigenetic Implications (Methylation)
   Cytosine methylation, specifically at the $\text{C5}$ position within CpG dinucleotides, is a crucial epigenetic modification in higher eukaryotes. While cytosine in a G–C context is the substrate, the stability imparted by the neighboring guanine residue appears to influence the accessibility of the $\text{C5}$ atom to DNA methyltransferases (DNMTs). Regions with high G–C de…