Download MendeleyRegulatory mechanisms of PP2A complex assembly driven by physicochemical differences in A-subunit isoforms.
Day, A., Huang, W., Leonard, D., O'Connor, C.M., Narla, G., Taylor, D.J.(2025) Structure
- PubMed: 40712571
- DOI: https://doi.org/10.1016/j.str.2025.06.013
- Primary Citation of Related Structures:
9MF5, 9MIP - PubMed Abstract:
Protein phosphatase 2A (PP2A) is crucial for regulating cellular pathways, with its holoenzyme assembly affecting enzyme function and substrate selection. The PP2A holoenzyme comprises scaffold A-, regulatory B-, and catalytic C-subunits, each with various isoforms. Here, we examine structural and biochemical characteristics of the A-subunit isoforms (Aα and Aβ) and identify different biophysical properties that may promote distinct PP2A functions. Our molecular dynamics simulations and cryo-EM analyses define structural differences in the isoforms that reside primarily at the N-terminus of the A-subunit where it interfaces with regulatory B-subunits. Kinetic analyses show Aβ has a lower binding affinity in complexes with B56 subunits and exhibits unique aggregative properties as a monomeric protein. These findings suggest that the different physicochemical properties between A-subunit isoforms are key to PP2A holoenzyme assembly and function. We predict that the Aβ serves as a reservoir, ensuring that serine-threonine phosphatase activity is maintained during high regulatory demand.
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA.
Organizational Affiliation:
