methyltransferase complex

Definition

Target type: cellularcomponent

A protein complex that possesses methyltransferase activity. [GOC:mah]

Methyltransferase complexes are multi-protein assemblies that play a crucial role in the transfer of methyl groups to various substrates, including DNA, RNA, proteins, and lipids. The cellular components of these complexes vary depending on the specific methyltransferase and its target molecule. However, some common components include:

**1. Catalytic subunit:** This is the core component of the complex and possesses the enzymatic activity responsible for transferring the methyl group. Different methyltransferases have distinct catalytic subunits tailored to their specific substrates.

**2. Regulatory subunits:** These subunits modulate the activity of the catalytic subunit. They can act as:
- **Scaffolding proteins:** They provide a structural framework for the complex, bringing together the catalytic and other regulatory subunits.
- **Substrate binding proteins:** They bind to the target molecule and present it to the catalytic subunit.
- **Cofactor binding proteins:** They bind and deliver essential cofactors, such as S-adenosyl methionine (SAM), the methyl donor.
- **Localization proteins:** They direct the complex to specific cellular locations, ensuring the correct methylation of target molecules.

**3. Accessory proteins:** These proteins are not essential for the catalytic activity but can enhance the efficiency or specificity of the complex. They might:
- **Modify the activity of the complex:** They can activate or inhibit the catalytic subunit or alter the affinity for specific substrates.
- **Stabilize the complex:** They can increase the stability and longevity of the complex.

**4. DNA/RNA/protein binding domains:** Some methyltransferases directly interact with their target molecules through specific domains. These domains recognize specific DNA sequences, RNA structures, or protein motifs, ensuring that the methylation occurs at the correct location.

The composition and organization of methyltransferase complexes can vary significantly depending on the specific methyltransferase and the cellular context. However, all these complexes share the common goal of mediating the transfer of methyl groups, contributing to diverse cellular processes, including DNA replication, repair, and gene expression.'
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Proteins (1)

Compounds (75)