Subunit of the 11S REG-gamma (also called PA28-gamma) proteasome regulator, a donut-shaped homoheptamer which associates with the proteasome. 11S REG-gamma activates the trypsin-like catalytic subunit of the proteasome but inhibits the chymotrypsin-like and postglutamyl-preferring (PGPH) subunits. Facilitates the MDM2-p53/TP53 interaction which promotes ubiquitination- and MDM2-dependent proteasomal degradation of p53/TP53, limiting its accumulation and resulting in inhibited apoptosis after DNA damage. May also be involved in cell cycle regulation.
Belongs to the PA28 family.
The C-terminal sequences affect heptamer stability and proteasome affinity.
Phosphorylated by MAP3K3.
Nucleus. Cytoplasm. Localizes to the cytoplasm during mitosis following nuclear envelope breakdown at this distinct stage of the cell cycle which allows its interaction with MAP3K3 kinase.