Core component of multiple cullin-RING-based ECS (ElonginB/C-CUL2/5-SOCS-box protein) E3 ubiquitin-protein ligase complexes, which mediate the ubiquitination of target proteins. CUL2 may serve as a rigid scaffold in the complex and may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1. The functional specificity of the ECS complex depends on the substrate recognition component. ECS(VHL) mediates the ubiquitination of hypoxia-inducible factor (HIF). A number of ECS complexes (containing either KLHDC2, KLHDC3, KLHDC10, APPBP2, FEM1A, FEM1B or FEM1C as substrate-recognition component) are part of the DesCEND (destruction via C-end degrons) pathway, which recognizes a C-degron located at the extreme C terminus of target proteins, leading to their ubiquitination and degradation. ECS complexes and ARIH1 collaborate in tandem to mediate ubiquitination of target proteins. Protein modification; protein ubiquitination. Component of multiple ECS (Elongin BC-CUL2/5-SOCS-box protein) E3 ubiquitin-protein ligase complexes formed of CUL2, Elongin BC (ELOB and ELOC), RBX1 and a variable substrate-specific adapter. Component of the ECS(VHL) or CBC(VHL) complex containing VHL. Component of the ECS(MED8) complex with the probable substrate recognition component MED8. Component of multiple ECS complexes part of the DesCEND (destruction via C-end degrons) pathway, which contain either KLHDC2, KLHDC3, KLHDC10, APPBP2, FEM1A, FEM1B or FEM1C as substrate-recognition component. Component of the ECS(LRR1) complex with the probable substrate recognition component LRR1. Component of a probable ECS E3 ubiquitin-protein ligase complex containing CUL2, RBX1, ELOB, ELOC and FEM1B. Part of an E3 ubiquitin-protein ligase complex including ZYG11B, CUL2 and Elongin BC. Part of an E3 ubiquitin-protein ligase complex including ZER1, CUL2 and Elongin BC. Interacts with RBX1, RNF7, FEM1B and TIP120A/CAND1. Found in a complex composed of LIMD1, VHL, EGLN1/PHD2, ELOB and CUL2. Interacts (when neddylated) with ARIH1; leading to activate the E3 ligase activity of ARIH1. Interacts (unneddylated form) with DCUN1D1, DCUN1D2, DCUN1D3, DCUN1D4 and DCUN1D5; these interactions promote the cullin neddylation. Component of VCB (elongins BC/CUL2/VHL) complex that contains at least DCUN1D1, CUL2 and VHL; this complex triggers CUL2 neddylation and consequently cullin ring ligase (CRL) substrates polyubiquitylation. Neddylated; which enhances the ubiquitination activity of ECS (Elongin BC-CUL2/5-SOCS-box protein) E3 ubiquitin-protein ligase complexes. CBC(VHL) complex formation seems to promote neddylation (By similarity). Deneddylated via its interaction with the COP9 signalosome (CSN) complex. Belongs to the cullin family.