PA: Protease-associated (PA) domain. 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 into which the PA domain is inserted include the following: i) various signal peptide peptidases including, hSPPL2a and 2b which catalyze the intramembrane proteolysis of tumor necrosis factor alpha, ii) various proteins containing a C3H2C3 RING finger including, Arabidopsis ReMembR-H2 protein and various E3 ubiquitin ligases such as human GRAIL (gene related to anergy in lymphocytes), iii) EDEM3 (ER-degradation-enhancing mannosidase-like 3 protein), iv) various plant vacuolar sorting receptors such as Pisum sativum BP-80, v) glutamate carboxypeptidase II (GCPII), vi) yeast aminopeptidase Y, vii) Vibrio metschnikovii VapT, a sodium dodecyl sulfate (SDS) resistant extracellular alkaline serine protease, viii) lactocepin (a cell envelope-associated protease from Lactobacillus paracasei subsp. paracasei NCDO 151), ix) various subtilisin-like proteases such as melon Cucumisin, and x) human TfR (transferrin receptor) 1 and 2.
Structure:1V6C_B, Pseudoalteromonas Sp. As-11, Apa1 protease, PA domain/ subtilisin-like domain interface, contacts at 3.5 A. - View structure with Cn3D
Structure:1SUV_A, human transferrin receptor TfR1 in complex with transferrin, contacts of PA domain with protease-like domain at 3.5A. - View structure with Cn3D
Jiyao W et al.(2023). "The conserved domain database in 2023.",