3mC

3mC, also known as 5-methylcytosine, is a type of DNA modification where a methyl group is added to the cytosine base. This modification occurs at the fifth carbon position of the cytosine ring, hence the name 5-methylcytosine. It is one of the most common forms of DNA methylation, which is a process that plays a crucial role in gene regulation, genomic stability, and epigenetic inheritance. DNA methylation can influence gene expression by altering the binding of transcription factors and other regulatory proteins to DNA. In mammals, DNA methylation is primarily associated with gene silencing, while in plants, it can both activate and repress gene expression. The process of DNA methylation is catalyzed by DNA methyltransferases, which transfer a methyl group from S-adenosylmethionine to the cytosine base. The pattern of DNA methylation can be dynamically regulated throughout an organism's lifetime, making it a key component of epigenetic regulation. Abnormal DNA methylation patterns have been linked to various diseases, including cancer, and are a subject of intense research in the field of epigenetics.