The coupling of ubiquitin conjugation to endoplasmic reticulum (ER) degradation (CUE) domain functions as a ubiquitin (UB) binding domain that is approximately 40 amino acids in length. Present in eukaryotic proteins that are involved in ubiquitination and protein trafficking pathways, CUE domains can bind monoubiquitin and may be required for ubiquitination of the proteins in which they are found. CUEDC1 (CUE domain-containing protein 1) is a 386 amino acid protein that contains one CUE domain, suggesting a possible role in protein trafficking and degradation pathways. Defects in the gene encoding CUEDC1 may be associated with early stage cervical cancer, implicating CUEDC1 as a potential tumor marker. Two isoforms of CUEDC1 exist due to alternative splicing events.