Substrate-recognition component of a Cul2-RING (CRL2) E3 ubiquitin-protein ligase complex 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 (PubMed:29779948, PubMed:29775578). The C-degron recognized by the DesCEND pathway is usually a motif of less than ten residues and can be present in full-length proteins, truncated proteins or proteolytically cleaved forms (PubMed:29779948, PubMed:29775578). The CRL2(APPBP2) complex specifically recognizes proteins with a -Arg-Xaa-Xaa-Gly degron at the C-terminus, leading to their ubiquitination and degradation (PubMed:29779948, PubMed:29775578). The CRL2(APPBP2) complex mediates ubiquitination and degradation of truncated SELENOV selenoproteins produced by failed UGA/Sec decoding, which end with a -Arg-Xaa-Xaa-Gly degron (PubMed:26138980). May play a role in intracellular protein transport: may be involved in the translocation of APP along microtubules toward the cell surface (PubMed:9843960). E3 ubiquitin-protein ligase activity of the CRL2(APPBP2) complex is inhibited by APP. Protein modification; protein ubiquitination. Component of a CRL2 E3 ubiquitin-protein ligase complex, also named ECS (Elongin BC-CUL2/5-SOCS-box protein) complex, composed of CUL2, Elongin BC (ELOB and ELOC), RBX1 and substrate-specific adapter APPBP2 (PubMed:29779948, PubMed:29775578). Interacts with APP; APP interaction inhibits the E3 ubiquitin-protein ligase activity of the CRL2(APPBP2) complex (PubMed:9843960, PubMed:29775578). Associated with membranes and microtubules. Rapidly degraded by the proteasome upon overexpression of a C-terminal fragment of APP.