### ANKRD9 Gene Summary

**Gene Symbol:** ANKRD9

**Function:** The ANKRD9 gene encodes a substrate receptor subunit of a cullin-RING E3 ubiquitin ligase complex, specifically the Cul5-RING complex. It has a crucial role in mediating ubiquitination and subsequent proteasomal degradation of target proteins, thereby regulating protein levels and cellular homeostasis.

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### Additional Information:

1. **Associated Genes:**
   - **IMPDH2 (Inosine 5'-Monophosphate Dehydrogenase 2):** As mentioned, ANKRD9 is involved in the regulation of IMPDH2, the enzyme that catalyzes the rate-limiting step in GTP synthesis.
   - **Cul5 (Cullin 5):** As part of the cullin-RING complex, ANKRD9 interacts with Cul5, which is essential to the ubiquitination process.
   - **RBX1 (RING Box Protein 1):** A component of the RING complex that works with cullins in ubiquitin ligase activity.
   - **Various other substrates of the ubiquitin proteasome system may indirectly relate to ANKRD9, although specific associations would require further exploration in literature.**

2. **Aging and Age-related Diseases:**
   - While specific studies focusing exclusively on ANKRD9's role in aging are limited, the regulation of proteasomal degradation through ubiquitin ligase activity is critical for cellular function and homeostasis. Dysregulation of the ubiquitin-proteasome system is known to contribute to age-related diseases and cellular senescence.
   - Given ANKRD9's role in regulating IMPDH2, which has implications in nucleotide metabolism, any disruptions in this metabolism may affect cellular aging and susceptibility to age-related disorders like cancer.

3. **Drug Interactions:**
   - While specific drugs directly interacting with ANKRD9 are not extensively documented, the modulation of proteasomal activity and related pathways suggests potential interactions with:
     - **Proteasome inhibitors** (e.g., Bortezomib, Carfilzomib) that can influence the ubiquitin-proteasome system and impact ANKRD9's function indirectly.
     - Some **copper chelators** or compounds used in the management of copper homeostasis disorders may also influence pathways where ANKRD9 is implicated, although direct interactions are less established.

4. **Pathways and Biological Processes:**
   - **Ubiquitin-mediated proteolysis:** ANKRD9 is integral to the ubiquitin-proteasome system, facilitating targeted protein degradation.
   - **Copper ion homeostasis:** The gene is involved in processes regulating copper levels, important for numerous biological functions.
   - **Cell proliferation:** ANKRD9 seems to play a role in controlling cell growth and division via its influence on key proteins involved in metabolic regulation.
   - **Signal Transduction:** The E3 ligase complex involving ANKRD9 can impact various signaling pathways through the degradation of specific protein substrates.

Overall, ANKRD9 plays a significant role in maintaining proteostasis and cellular metabolism through its function in ubiquitination and its involvement in copper ion homeostasis. Its dysregulation could have implications in various biological processes and diseases, especially age-related conditions.