### AP4E1 Gene Overview

**Gene Symbol:** AP4E1  
**Location:** Chromosome 3  
**Gene Function:** The AP4E1 gene encodes a large subunit of the adaptor protein complex 4 (AP-4), which plays a vital role in intracellular protein transport. It is involved in various pathways, mediating the formation and sorting of vesicles in secretory and endocytic pathways.

### 1. Associated Genes
While the summaries provided do not explicitly list interacting or associated genes, AP4E1 is functionally linked with several genes involved in vesicle trafficking and signaling, including:

- **AP4B1** (adaptor protein complex 4 sigma 1 subunit)
- **AP4G1** (adaptor protein complex 4 gamma 1 subunit)
- **AP4S1** (adaptor protein complex 4 sigma 2 subunit)
- **DCTN1** (dynactin subunit 1), linked to vesicle transport and neurodegeneration.
- **SNAP25** (synaptosomal-associated protein 25), involved in neurotransmitter release.

### 2. Aging and Age-Related Diseases
The AP4E1 gene has been implicated in various neurological disorders. While specific aging-related studies on AP4E1 may be limited, disruptions in intracellular trafficking pathways, where AP-4 is crucial, could contribute to age-related neurodegeneration or disorders like Alzheimer’s disease. Research indicates that neuronal protein distribution and synaptic function may decline with age due to impaired vesicle trafficking, potentially highlighting a role for AP4E1 in age-associated cognitive decline.

### 3. Drug Interactions
Currently, specific drugs or drug classes that directly interact with the AP4E1 gene or its protein product have not been broadly characterized. However, understanding the function of AP-4 may inform future drug development aimed at treating conditions linked with vesicular transport deficiencies. Further research may uncover therapeutics targeting pathways involving AP-4 or indirectly influencing its activity.

### 4. Pathways and Biological Processes
AP4E1 plays a critical role in several biological pathways, including:

- **Vesicle-mediated transport:** Integral to the formation and trafficking of vesicles originating from the trans-Golgi network (TGN) to the endosomal-lysosomal system.
- **Protein sorting:** Involved in the selection of cargo proteins for transport, particularly in basolateral membrane targeting in epithelial cells.
- **Endocytic pathway regulation:** Facilitates the uptake of membrane proteins involved in various signal transduction pathways.
- **Neuronal function localizations:** Contributes to the asymmetric localization of proteins in neurons, which is essential for maintaining neuronal polarity and function.

### Summary
The AP4E1 gene is essential for the proper functioning of adaptor protein complex 4, impacting vesicle transport and sorting within cells. Its disruption may lead to neurological conditions, including cerebral palsy, and holds potential implications for age-associated neurodegeneration. Further elucidation of its pathways and interactions will continue to advance our understanding of its role in cell biology and disease.