PA_hSPPL_like: Protease-associated domain containing human signal peptide peptidase-like (hSPPL)-like. This group contains various PA domain-containing proteins similar to hSPPL2a and 2b. These SPPLs are GxGD aspartic proteases. SPPL2a is sorted to the late endosomes, SPPL2b to the plasma membrane. In activated dendritic cells, hSPPL2a and 2b catalyze the intramembrane proteolysis of tumor necrosis factor alpha triggering IL-12 production. hSPPL2a and 2b may have a broad substrate spectrum. The significance of the PA domain to these SPPLs has not been ascertained. 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.
Jiyao W et al.(2023). "The conserved domain database in 2023.",