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PA_2: Protease-associated (PA) domain subgroup 2. A subgroup of PA-domain containing proteins. The PA domain is an insert domain in a diverse fraction of proteases. The significance of the PA domain to many of the proteins in which it is inserted is undetermined. It may be a protein-protein interaction domain. At peptidase active sites, the PA domain may participate in substrate binding and/or promoting conformational changes, which influence the stability and accessibility of the site to substrate. Proteins in this group contain a C-terminal RING-finger domain. Proteins into which the PA domain is inserted include the following: i) various signal peptide peptidases: such as hSPPL2a and 2b, ii) various E3 ubiquitin ligases similar to human GRAIL (gene related to anergy in lymphocytes) protein, iii) various proteins containing a RING finger motif such as Arabidopsis ReMembR-H2 protein, iv) EDEM3 (ER-degradation-enhancing mannosidase-like 3 protein), v) various plant vacuolar sorting receptors such as Pisum sativum BP-80, vi) prostate-specific membrane antigen (PSMA), vii) yeast aminopeptidase Y viii) Vibrio metschnikovii VapT, a sodium dodecyl sulfate (SDS) resistant extracellular alkaline serine protease, ix) various subtilisin-like proteases such as Cucumisin from the juice of melon fruits, and x) human TfR (transferrin receptor) 1 and human TfR2. The proteins listed above belong to other subgroups; relatively little is known about proteins in this subgroup.
Jiyao W et al.(2023). "The conserved domain database in 2023.",