Proteasome subunit beta type-7 (PSMB7)

Proteasome subunit beta type-7 (PSMB7) is the constitutive β2 subunit of the 20S proteasome core particle, contributing the protease’s trypsin-like activity that cleaves after basic residues. The 20S core is a barrel of four stacked heptameric rings (α7–β7–β7–α7); three β subunits (β1, β2, β5) provide the N-terminal threonine active sites facing the inner chamber where proteolysis occurs. PSMB7 (β2) is incorporated into the two inner β rings and participates in ATP/ubiquitin-dependent protein degradation when the 20S core is capped by regulatory particles (e.g., 19S) and in ubiquitin-independent degradation when associated with PA28/PA200. In immune contexts, interferon-γ can favor replacement of β2 by the inducible β2i in immunoproteasomes, affecting peptide generation for MHC class I presentation.

Other names

20S proteasome subunit beta-2 (systematic β2)Proteasome 20S subunit beta 7PSMB7 (gene symbol)

Covalent or reversible inhibition of 20S proteasome catalytic sites within the β-ring, blocking proteolysis and leading to accumulation of ubiquitinated proteins, cell-cycle arrest, and apoptosis in malignant cells. Some inhibitors preferentially target β5 but can affect β1/β2 activities; β2 corresponds to trypsin-like activity contributed by PSMB7