Post-translational ubiquitin-protein conjugates are recognised for degradation by the ubiquitin fusion degradation (UFD) pathway. Several proteins involved in this pathway have been identified PMID:7615550. This superfamily includes UFD1, a 40kD protein that is essential for vegetative cell viability PMID:7615550. The human UFD1 gene is expressed at high levels during embryogenesis, especially in the eyes and in the inner ear primordia and is thought to be important in the determination of ectoderm-derived structures, including neural crest cells. In addition, this gene is deleted in the CATCH-22 (cardiac defects, abnormal facies, thymic hypoplasia, cleft palate and hypocalcaemia with deletions on chromosome 22) syndrome. This clinical syndrome is associated with a variety of developmental defects, all characterised by microdeletions on 22q11.2. Two such developmental defects are the DiGeorge syndrome OMIM:188400 and the velo-cardio-facial syndrome OMIM:145410. Several of the abnormalities associated with these conditions are thought to be due to defective neural crest cell differentiation.

PFAM:PF03152

Ufd1 is part of the Ufd1-Npl4 complex that functions as the substrate-recruiting cofactor for Cdc48 segregase. The Cdc48-Ufd1-Npl4 complex is involved in degradation of misfolded ER proteins PMID:20206597. The Ufd1-Npl4 complex has been found to recruit Cdc48 to ubiquitylated CMG (Cdc45-MCM-GINS) helicase at the end of chromosome replication, thereby driving the disassembly reaction PMID:28355556. In humans, Npl4-Ufd1 acts as a cofactor in reducing antiviral innate immune responses by facilitating proteasomal degradation of RIG-I (a viral RNA sensor) PMID:26471729.

INTERPRO:IPR004854