Substrate-recognition component of a DCX (DDB1-CUL4-X-box) 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:16949367, PubMed:16964240, PubMed:29779948). 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). The DCX(DCAF12) complex specifically recognizes proteins with a diglutamate (Glu-Glu) at the C-terminus, such as MAGEA3, MAGEA6 and CCT5, leading to their ubiquitination and degradation (PubMed:29779948, PubMed:31267705). Ubiquitination of MAGEA3, MAGEA6 by DCX(DCAF12) complex is required for starvation-induced autophagy (PubMed:31267705). Protein modification; protein ubiquitination. Component of the DCX(DCAF12) E3 ubiquitin ligase complex, at least composed of CUL4 (CUL4A or CUL4B), DDB1, DCAF12 and RBX1. Highly expressed in lung cancer tissues and some cancer cell lines (PubMed:18957058). Restricted expression in normal testis (PubMed:18957058). Belongs to the WD repeat DCAF12 family.