Serine/threonine-protein phosphatase 2A 56 kDa regulatory subunit alpha isoform

PPP2R5A encodes a 56 kDa regulatory subunit of protein phosphatase 2A (PP2A), a serine/threonine phosphatase complex. The B regulatory subunit modulates substrate selectivity and catalytic activity of the PP2A holoenzyme and directs its localization to specific subcellular compartments (UniProt: Q15172).

PP2A and its regulatory subunits are implicated in neuronal signaling and protein homeostasis pathways relevant to neurodegeneration. The protein is expressed in human brain tissue and participates in phosphatase-mediated regulation of cellular processes.

PPP2R5A shows increased abundance in Alzheimer's disease brain tissue. Quantitative proteomics analysis of post-mortem AD brain compared to age-matched controls detected PPP2R5A as upregulated (mean log2 fold-change: 0.26) in one subcellular fraction (Chaparral AD proteomics). This modest upregulation may reflect altered PP2A regulation or compensatory phosphatase activity in the AD brain proteome.