### GZMK Gene Overview

**Gene Symbol**: GZMK

**Function**: The GZMK gene encodes a serine protease that is primarily found in the cytoplasmic granules of cytotoxic lymphocytes, such as cytolytic T lymphocytes (CTL) and natural killer (NK) cells. This enzyme plays a critical role in the immune response by facilitating the lysis of target cells bearing 'nonself' antigens, typically presented by infected or transformed cells. The absence of N-glycosylation consensus sequences in its structure distinguishes GZMK from other members of the granzyme family. 

**Tissue Expression**: GZMK is primarily expressed in several key tissues, including the lung, spleen, thymus, and peripheral blood leukocytes, which are crucial for immune function.

### 1. Associated Genes
GZMK has been identified in various contexts with other genes that may have roles in immune response, apoptosis, and inflammation. Notably, it is often studied alongside other granzyme genes (e.g., GZMA, GZMB, GZMC) and genes related to T cell activation and proliferation. Relevant gene interactions include:

- **TGFB1**: Associated with TGF-beta signaling, critical for immune modulation.
- **FAS and FASL**: Involved in apoptosis pathways that are activated during immune responses.
- **PERFORIN**: Works in concert with granzymes to mediate cytotoxicity.

### 2. Aging and Age-Related Diseases
While specific direct associations between GZMK and aging or age-related diseases are still being explored, broader research on immune system functioning suggests the following:

- **Immunosenescence**: The decline in immune function with age, potentially leading to altered GZMK expression or activity, may contribute to age-related conditions by impairing the body’s ability to respond to infection or malignancies.
- **Chronic Inflammatory Diseases**: Elevated levels of cytotoxic lymphocytes and altered granzyme expression have been implicated in chronic disorders such as rheumatoid arthritis and atherosclerosis, which are more common in older adults.

### 3. Drug Interactions
Currently, specific drugs that interact directly with GZMK are not well defined in the literature. However, several classes of drugs that modulate the immune response could potentially influence the function or expression of GZMK, including:

- **Immunosuppressants**: Medications like corticosteroids and calcineurin inhibitors may alter the activity or expression of granzyme-associated genes in lymphocytes.
- **Chemotherapy agents**: Certain cancer treatments can induce apoptosis in cancer cells, which may intersect with the functions of GZMK and other granzyme products when CTLs are activated.

### 4. Pathways and Biological Processes
GZMK is involved in several important biological pathways and processes:

- **Cytotoxic Granule Pathway**: Integral to the process where granules containing GZMK and perforin are released upon recognition of infected or malignant cells, leading to their destruction.
- **T cell Activation and Differentiation**: Plays a role in the activation of CTLs and their differentiation into effector cells capable of targeting specific antigens.
- **Immune Response**: Participates in the immune response against viral infections and tumor surveillance.

Additionally, GZMK may be involved in signal transduction pathways associated with cell death and inflammation, highlighting its potential role in maintaining homeostasis in the immune system.

### Conclusion
The GZMK gene plays a crucial role in the cytotoxic function of immune cells, with implications in both health and disease, particularly regarding immune responses, aging, and potential therapeutic avenues. Further research is necessary to elucidate all interactions and pathways fully involving GZMK in the context of human biology.