### SEMA4B Gene Overview

**Gene Symbol**: SEMA4B  
**Chromosomal Location**: 1q22  
**NCBI Gene ID**: 10020  
**UniProt Accession**: Q9Y6M6  
**Protein Length**: 1,101 amino acids  

### Function and Characteristics
SEMA4B (Semaphorin 4B) belongs to the semaphorin family of proteins, which play critical roles in various developmental processes, especially in the nervous system. It is implicated in chemorepellent activity, which is the ability to repel axons or other cellular structures during development. This gene primarily functions in neuronal processes, including:

- Neuron generation
- Neural crest cell migration
- Semaphorin-plexin signaling pathways

The protein encoded by SEMA4B is predicted to localize in the plasma membrane, functioning within the extracellular space, and is categorized as an integral component of the plasma membrane. Importantly, it is known to inhibit axonal extension by creating signals that delineate territories that are inaccessible to growing axons.

### Associated Genes
While the summaries you provided do not name specific associated genes, **SEMA4B** is known to interact with members of the Plexin and Neuropilin families, which are receptors for semaphorins. Other genes within the broader semaphorin family may also show involvement in pathways where SEMA4B is active, such as:

- **SEMA3A, SEMA3B, SEMA3C, SEMA3D**: Other semaphorins with overlapping functions but differing receptor specificities.
- **PLXNA4, PLXNG1**: Plexins that serve as receptors for semaphorins and partner in the signaling mechanisms.

### Aging and Age-Related Diseases
While direct associations of SEMA4B with aging are not extensively defined in literature, there are emerging studies that suggest roles for semaphorins in neurodegenerative diseases. SEMA4B might indirectly be involved in:

- **Neurodegeneration**: Its function in axonal growth and connectivity could imply a role in maintaining neural networks that may decline with age.
- **Cognitive decline**: Alteration in semaphorin signaling has been proposed in models of cognitive impairment and neurodevelopmental disorders.

However, more targeted research is needed to elucidate the exact contribution of SEMA4B in aging or specific age-related diseases.

### Drug Interactions
As of the latest data updates, there are no specific drugs or drug classes that are directly indicated to interact with SEMA4B itself. However, since SEMA4B is involved in neurodevelopmental processes, altered signaling through semaphorins can suggest potential implications for drugs targeting neurodevelopmental or neurodegenerative diseases, but specific interactions would need to be validated in clinical settings.

### Pathways and Biological Processes
SEMA4B is involved in several biological and signaling pathways, which include:

1. **Semaphorin signaling pathway**: Promoting repulsion in axonal guidance and influencing neural network formations.
2. **Neurodevelopmental pathway**: Critical for normal brain development, particularly concerning the migration and positioning of neurons.
3. **Cell adhesion and migration**: Roles in facilitating the movement of neural crest cells, which are essential in embryonic development.
4. **Axon guidance**: As SEMA4B inhibits axonal extension, it plays a significant role in defining trajectory and territories during the formation of the nervous system.

### Conclusion
In summary, the SEMA4B gene plays a pivotal role in neural development and signaling, with potential implications in aging and neurodegenerative diseases, although specific drugs interacting directly with this gene have not been clearly identified. Further studies may enhance our understanding of SEMA4B's role in various biological contexts, particularly concerning its involvement in the nervous system and potential therapeutic targets.