Proteasome subunit alpha type-2

PSMA2 (proteasome subunit alpha type-2) is a core component of the 20S proteasome complex, which catalyzes ATP-dependent degradation of ubiquitinated proteins and participates in ubiquitin-independent proteolysis when associated with regulatory particles such as PA200 or PA28 (UniProt: P25787). The protein maintains cellular protein homeostasis by removing misfolded, damaged, or functionally obsolete proteins, and contributes to antigen presentation and spermatogenesis through distinct proteasomal assemblies.

PSMA2 is broadly expressed and plays essential roles across multiple cellular pathways dependent on proteasomal function (UniProt: P25787). No primary disease associations are documented in UniProt for this protein.

In Alzheimer's Disease, PSMA2 is significantly downregulated in post-mortem AD brain tissue compared to age-matched controls (Chaparral AD proteomics). TMT-labeled quantitative proteomics across four subcellular fractions yielded a mean log2 fold-change of −0.39, indicating reduced proteasomal capacity (ad:direction:down). Diminished proteasome subunit abundance may reflect impaired protein quality control and contribute to the pathological accumulation of misfolded proteins characteristic of AD neurodegeneration.