### METTL21C Gene Overview

**Gene Symbol:** METTL21C  
**Function:** METTL21C encodes a protein that exhibits protein-lysine N-methyltransferase activity and is involved in protein methylation. It is known to bind to heat shock proteins and plays a role in the regulation of various cellular processes. This gene is primarily localized in the nucleus and is part of a protein-containing complex.

### 1. Associated Genes
While the summaries provided do not explicitly list associated genes, METTL21C has been studied in relation to several other genes involved in protein modification and stress responses. Notably:
- **HSP70 (Heat Shock Protein 70)**
- **HSP90 (Heat Shock Protein 90)**
- **METTL21B**, which is closely related and may function similarly in methylation processes.
- **PRMTs (Protein Arginine Methyltransferases)**, as they're often involved in similar post-translational modification pathways.

### 2. Aging and Age-related Diseases
Research concerning METTL21C in the context of aging is still in its investigative stages. However, protein methylation is recognized as a significant post-translational modification related to cellular signaling and stress responses, which can affect aging processes and contribute to age-related diseases like:
- **Neurodegenerative Disorders**: Altered protein methylation can influence protein aggregation or misfolding, relevant to conditions such as Alzheimer’s disease.
- **Cancer**: Methylation modifications are often altered in various cancers, suggesting its potential role in tumorigenesis through implications in DNA repair and gene expression regulation.

### 3. Interactions with Drugs or Drug Classes
As of now, there is limited data specifically correlating METTL21C with drugs or drug classes. Nevertheless, because it is involved in processes that are often targeted in therapeutic contexts, it may interact indirectly with:
- **Cancer therapeutics**: Drugs targeting pathways modified by protein methylation (like histone methyltransferase inhibitors) could influence the activity or expression of METTL21C indirectly.

### 4. Pathways and Biological Processes
METTL21C is involved in several key biological processes and pathways, including:
- **Protein methylation**: Involved in the modification of lysine residues on target proteins.
- **Regulation of Protein Stability**: Methylation can affect protein folding, stability, and interactions.
- **Heat Shock Response**: Due to its binding activity with heat shock proteins, it is implicated in the cellular response to stress conditions such as elevated temperatures.
- **Cell Cycle Regulation**: Methylation modifications are fundamental in regulating the cell cycle and can influence cellular growth and division.

### Summary
METTL21C is a significant player in the realm of protein methylation, exhibiting specific binding and modifying activities essential for proper cellular function and stress response. As research continues, its precise roles in aging and associated diseases, as well as interactions with pharmacological agents, are likely to be elucidated further.