histone H3K9 methyltransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: S-adenosyl-L-methionine + histone H3 L-lysine (position 9) = S-adenosyl-L-homocysteine + histone H3 N6-methyl-L-lysine (position 9). This reaction is the addition of up to three methyl groups to the lysine residue at position 9 of the histone H3 protein. [GOC:ai]

Histone H3K9 methyltransferase activity is a molecular function that refers to the enzymatic ability to transfer a methyl group from a donor molecule, like S-adenosyl methionine (SAM), to the lysine residue at position 9 of histone H3. This methylation event is a crucial epigenetic modification that plays a key role in regulating gene expression. Histone H3K9 methylation can result in various levels of methylation, including mono-, di-, and tri-methylation, each with distinct functional implications.

Tri-methylation of H3K9 (H3K9me3) is often associated with gene silencing. This modification attracts heterochromatin proteins, which promote the formation of condensed chromatin structures that are inaccessible to transcription factors, thereby inhibiting gene expression. On the other hand, mono-methylation of H3K9 (H3K9me1) can be associated with gene activation, while di-methylation (H3K9me2) has been linked to both gene silencing and activation, depending on the specific context.

Histone H3K9 methyltransferases (HMTs) are enzymes responsible for catalyzing this methylation reaction. These enzymes are highly specific for their target histone residue and exhibit different regulatory roles depending on their cellular context. For instance, some HMTs are involved in establishing and maintaining heterochromatin, while others play a role in development and differentiation.

The molecular function of histone H3K9 methyltransferase activity is critical for maintaining genomic stability, regulating gene expression, and controlling cellular processes like cell cycle progression and differentiation. It is a key player in the intricate dance of epigenetic regulation, which allows for dynamic and reversible modifications of DNA and associated proteins, ultimately influencing gene expression patterns.'
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Proteins (6)

Compounds (32)