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

PPP2R5B encodes the 56 kDa regulatory subunit beta of protein phosphatase 2A (PP2A), a component that assembles into the PP2A holoenzyme to modulate substrate specificity, subcellular localization, and phosphorylation responsiveness (UniProt: Q15173). Within the PP2A complex, PPP2R5B mediates interactions with AKT1, facilitating its dephosphorylation and linking PP2A activity to AKT1 signaling regulation.

PP2A regulatory subunits are involved in serine/threonine phosphatase signaling across multiple cellular compartments and pathways. No primary disease associations are documented in UniProt for PPP2R5B.

PPP2R5B shows downregulation in Alzheimer's disease brain tissue compared to age-matched controls (ad:direction:down), with a mean log2 fold-change of −0.22 in human post-mortem AD brain assessed by TMT-labeled DDA proteomics across subcellular fractions (Chaparral AD proteomics). This modest reduction suggests potential alterations in PP2A-mediated dephosphorylation of AKT and other substrates in AD pathology, though the functional consequences warrant further investigation.