ASB7 (ankyrin repeat and SOCS box containing 7) functions as a substrate-recognition component of the CUL5-based E3 ubiquitin ligase complex (ECS), which mediates proteasomal degradation of target proteins 1. ASB7 employs its ankyrin repeats 3-6 to form an extended groove that recognizes conserved helical degrons through electrostatic and hydrophobic interactions 2. A primary physiological role involves negative regulation of H3K9me3 homeostasis: ASB7 is recruited to heterochromatin by HP1α (CBX5) where it promotes SUV39H1 degradation, preventing excessive heterochromatin formation 1. During mitosis, CDK1-mediated phosphorylation of ASB7 inactivates it, allowing SUV39H1 stabilization and H3K9me3 restoration 1. ASB7 also regulates spindle dynamics and genome integrity by targeting PSRC1 and DDA3 for degradation in a cell cycle-dependent manner 3. Additionally, ASB7 expression is upregulated under endoplasmic reticulum stress and associates with unfolded protein response activation 4. Clinically, ASB7 variants were identified in genome-wide association studies as associated with optic cup area, suggesting relevance to glaucoma pathogenesis 5. These findings establish ASB7 as a critical regulator of epigenetic homeostasis, mitotic progression, and cellular stress responses.