Substrate-recognition component of a Cul5-RING (CRL5) 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:32200094). 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:32200094). The CRL5(KLHDC1) complex mediates ubiquitination and degradation of truncated SELENOS selenoprotein produced by failed UGA/Sec decoding, which ends with a glycine (PubMed:32200094). Protein modification; protein ubiquitination. Component of a CRL5 E3 ubiquitin-protein ligase complex, also named ECS (Elongin BC-CUL2/5-SOCS-box protein) complex, composed of CUL5, Elongin BC (ELOB and ELOC), RBX1 and substrate-specific adapter KLHDC1. Widely expressed, with high levels in skeletal muscle, pancreas and liver. Undetectable in peripheral blood leukocytes.