Proteasome subunit beta type-6 (PSMB6)

The 20S proteasome β1 subunit, scientifically known as Proteasome subunit beta type-6 (PSMB6), is a core catalytic component of the eukaryotic 20S proteasome (UniProt P28072) [5]. It is responsible for the caspase-like or post-acidic proteolytic activity, which involves the cleavage of peptide bonds following acidic amino acid residues [1, 13]. As part of the ubiquitin-proteasome system (UPS), PSMB6 is vital for maintaining cellular protein homeostasis by degrading misfolded, damaged, or regulatory proteins [1, 5]. In response to inflammatory signals like interferon-gamma, PSMB6 can be replaced by its inducible counterpart, PSMB9 (β1i), to form the immunoproteasome [11, 15]. PSMB6 is a major therapeutic target in the treatment of hematological malignancies, such as multiple myeloma and mantle cell lymphoma [1, 9]. Proteasome inhibitors like bortezomib and carfilzomib bind to the active-site threonine of PSMB6 and other catalytic subunits, leading to the toxic accumulation of proteins, induction of the unfolded protein response, and apoptosis in cancer cells [13]. Beyond oncology, PSMB6 dysfunction is implicated in neurodegenerative and autoimmune diseases [2, 10]. Monitoring PSMB6 activity and genetic variants can provide insights into drug resistance and patient response to proteasome-targeted therapies [9, 12].

Other names

20S proteasome subunit beta-1PSMB6DELTALMPYProteasome delta chainMacropain delta chainMulticatalytic endopeptidase complex delta chainProteasome subunit YBeta-1

Proteasome inhibition; specifically, these drugs bind to the N-terminal threonine active site of the catalytic beta subunits (β1, β2, and β5) of the 20S proteasome, blocking their proteolytic activities [13]. PSMB6 (β1) provides the caspase-like activity [1, 13]. This inhibition leads to the accumulation of polyubiquitinated proteins, triggering endoplasmic reticulum stress and apoptosis [13].