Members of this family are the Pup--protein ligase PafA (proteasome accessory factor A), a protein shown to regulate steady-state levels of certain proteasome targets in Mycobacterium tuberculosis. Iyer, et al (2008) first suggested that PafA is the ligase for Pup, a ubiquitin analog attached to an epsilon-amino group of a Lys side-chain to direct the target to the proteasome. [Protein fate, Degradation of proteins, peptides, and glycopeptides]
Jiyao W et al.(2023). "The conserved domain database in 2023.",