Ubiquitin regulatory domain X (UBX) found in UBX domain protein 8 (UBXN8) and similar proteins
UBXN8, also termed reproduction 8 protein (Rep8), or UBX domain-containing protein 6 (UBXD6), or D8S2298E, belongs to the UBXD family of proteins that contains the ubiquitin regulatory domain X (UBX) with a beta-grasp ubiquitin-like fold, but without the C-terminal double glycine motif. UBX domain is typically located at the carboxyl terminus of proteins, and participates broadly in the regulation of protein degradation. UBXN8 functions as a cofactor of p97 (also known as VCP or Cdc48), which is a homohexameric AAA ATPase (ATPase associated with a variety of activities) involved in a variety of functions ranging from cell-cycle regulation to membrane fusion and protein degradation. UBXN8 is a transmembrane protein that localizes to the endoplasmic reticulum (ER) membrane with its UBX domain facing the cytoplasm. It facilitates efficient ER-associated degradation (ERAD) by tethering p97 to the ER membrane.
Feature 1:putative UBX-p97 interaction site [polypeptide binding site]
Evidence:
Comment:based on the structural evidence of the Rattus norvegicus UBX domain of p47/UBXN2C (1S3S) bound with p97, contacts at 4A
Comment:Hexameric p97 N terminal domains are complexed with UBX domain of p47 through a loop that is highly conserved in UBX domains but is absent in ubiquitin.
Jiyao W et al.(2023). "The conserved domain database in 2023.",