PSME3 is a member of the PA28 family. The 26S proteasome is an extremely organized multicatalytic proteinase complex composed of 2 complexes， a 20S core and a 19S regulator. Proteasomes are spread all over the eukaryotic cells in large quantities and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. PSME3 stimulates the trypsin-like catalytic subunit of the proteasome and inhibits the chymotrypsin-like and postglutamyl-preferring （PGPH） subunits. PSEM3 enables the MDM2-p53/TP53 collaboration that encourages ubiquitination- and MDM2-dependent proteasomal degradation of p53/TP53， restricting its growth and causing inhibited apoptosis after DNA damage.
