Protein phosphatase 2A regulatory subunit B56 alpha (PP2A-B56α)

**Protein phosphatase 2A regulatory subunit B56 alpha (PP2A-B56α)** is one of several regulatory subunits (B56 family: α, β, γ, δ, ε) that associate with the core enzyme of protein phosphatase 2A (PP2A), a highly conserved serine/threonine phosphatase. PP2A-B56α determines substrate specificity, subcellular localization, and activity of the PP2A holoenzyme[1][3]. It plays crucial roles in cell cycle progression, such as regulating p53 via Cyclin G and participating in Wnt signaling. This subunit is primarily cytoplasmic but can shuttle between cellular compartments. It modulates apoptosis by associating with Bcl2 at mitochondrial membranes and promoting its dephosphorylation in response to apoptotic signals like ceramide[2]. Altered PP2A-B56α function has been implicated in cancer, with deregulation affecting cell adhesion, migration, and survival pathways[1][3]. No drugs selectively target B56α, but as a regulatory subunit of a major enzyme system, it is an important contributor within the PP2A complex that is considered a therapeutic target in several diseases.

Other names

PP2A regulatory subunit B' alphaB56αPR61APPP2R5A

Modulation of dephosphorylation of key substrates (e.g., Bcl2 via PP2A-B56α, affecting apoptosis); Regulation of cell signaling pathways relevant for cell survival and proliferation