Proteasome subunit beta type 1 (PSMB1) and Proteasome subunit beta type 2 (PSMB2) (PSMB1 and PSMB2)

Proteasome subunit beta type 1 (PSMB1) and Proteasome subunit beta type 2 (PSMB2) are essential catalytic components of the 20S core particle within the 26S proteasome complex (UniProt: P20618, P49721). PSMB1 exhibits caspase-like activity, while PSMB2 possesses trypsin-like activity, both contributing to the degradation of polyubiquitinated proteins (PubMed: 10651330). This degradation process is critical for maintaining cellular proteostasis, regulating the cell cycle, and modulating signal transduction pathways such as NF-kappaB (PubMed: 15546726). In many cancers, particularly hematologic malignancies like multiple myeloma, the proteasome is overactive to handle the high protein synthesis load, making it a validated therapeutic target (PubMed: 21149815). Drugs like bortezomib and carfilzomib inhibit these subunits, leading to the accumulation of misfolded proteins, induction of the unfolded protein response, and ultimately, apoptosis of the malignant cells (DrugBank: DB00188, DB08889). While PSMB5 is often the primary target for chymotrypsin-like activity, the inhibition of PSMB1 and PSMB2 contributes to the overall efficacy and overcomes resistance mechanisms in proteasome-targeted therapies (PubMed: 23539236). This dual targeting approach is a key strategy in the development of next-generation proteasome inhibitors aimed at overcoming clinical resistance (PubMed: 21149815).

Other names

PSMB1PSMB2Proteasome component C7-IProteasome component C7-IIBeta1Beta2PSC7PSC10Macropain subunit C7-IMacropain subunit C7-IIProteasome subunit beta type-1Proteasome subunit beta type-2

Inhibition of the 20S proteasome catalytic activity by binding to the N-terminal threonine residues of the beta subunits, thereby blocking the degradation of polyubiquitinated proteins (PubMed: 15546726, 21149815).