Substrate recognition component of a SCF-like ECS (Elongin BC-CUL2/5-SOCS-box protein) E3 ubiquitin-protein ligase complex which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (By similarity). Negatively regulates nitric oxide (NO) production and limits cellular toxicity in activated macrophages by mediating the ubiquitination and proteasomal degradation of NOS2 (By similarity). Acts as a bridge which links NOS2 with the ECS E3 ubiquitin ligase complex components ELOC and CUL5 (By similarity). Diminishes EphB2-dependent cell repulsive responses by mediating the ubiquitination and degradation of the EphB2/CTF2 (By similarity). Regulates cellular clock function by mediating ubiquitination and proteasomal degradation of the circadian transcriptional repressor NR1D1 (By similarity). Protein modification; protein ubiquitination. Component of the probable ECS(SPSB4) E3 ubiquitin-protein ligase complex which contains CUL5, RNF7/RBX2, Elongin BC complex and SPSB4 (By similarity). Interacts with CUL5; RNF7; ELOB and ELOC (By similarity). Interacts with MET (PubMed:16369487). Interacts (via B30.2/SPRY domain) with PAWR; this interaction occurs in association with the Elongin BC complex (PubMed:16369487, PubMed:20561531). Interacts with NOS2 (PubMed:20603330). Interacts with EPHB2 (By similarity). Exhibits a diffuse cytosolic localization. The SOCS box domain mediates the interaction with the Elongin BC complex, an adapter module in different E3 ubiquitin ligase complexes (By similarity). Essential for its ability to link NOS2 and the ECS E3 ubiquitin ligase complex components ELOC and CUL5 (By similarity). Belongs to the SPSB family.