Substrate-recognition component of a cullin-5-RING E3 ubiquitin-protein ligase complex (ECS complex, also named CRL5 complex), which mediates the ubiquitination and subsequent proteasomal degradation of target proteins, such as LZTS1, PSRC1 and SUV39H1 (PubMed:16325183, PubMed:27697924, PubMed:39039081, PubMed:40440427). The ECS(ASB7) complex acts as a negative regulator of H3K9me3 histone mark by mediating ubiquitination and degradation of SUV39H1: ASB7 is recruited to heterochromatin by CBX5 (HP1 alpha), where it associates with SUV39H1, promoting the ubiquitin-proteasome-mediated degradation of SUV39H1 (PubMed:40440427). During mitosis, ASB7 is phosphorylated and inactivated, allowing SUV39H1 activity (PubMed:40440427). The ECS(ASB7) complex also plays a role in spindle dynamics and genome integrity by targeting the mitotic progression protein PSRC1 for proteasomal degradation in a cell cycle-dependent manner (PubMed:27697924). Also participates in meiosis by mediating the proper attachment between kinetochores and microtubules (By similarity). {ECO:0000250|UniProtKB:Q91ZU0, ECO:0000269|PubMed:16325183, ECO:0000269|PubMed:27697924, ECO:0000269|PubMed:39039081, ECO:0000269|PubMed:40440427}. This is the function of ASB7 (ankyrin repeat and SOCS box containing 7, Ensembl gene identifier ENSG00000183475).