2iae
From Proteopedia
Crystal structure of a protein phosphatase 2A (PP2A) holoenzyme.
Structural highlights
Function[2AAA_MOUSE] The PR65 subunit of protein phosphatase 2A serves as a scaffolding molecule to coordinate the assembly of the catalytic subunit and a variable regulatory B subunit. Required for proper chromosome segregation and for centromeric localization of SGOL1 in mitosis (By similarity). [PP2AA_HUMAN] PP2A is the major phosphatase for microtubule-associated proteins (MAPs). PP2A can modulate the activity of phosphorylase B kinase casein kinase 2, mitogen-stimulated S6 kinase, and MAP-2 kinase. Cooperates with SGOL2 to protect centromeric cohesin from separase-mediated cleavage in oocytes specifically during meiosis I (By similarity). Can dephosphorylate SV40 large T antigen and p53/TP53. Activates RAF1 by dephosphorylating it at 'Ser-259'.[1] [2] [3] [2A5G_HUMAN] The B regulatory subunit might modulate substrate selectivity and catalytic activity, and also might direct the localization of the catalytic enzyme to a particular subcellular compartment. The PP2A-PPP2R5C holoenzyme may specifically dephosphorylate and activate TP53 and play a role in DNA damage-induced inhibition of cell proliferation. PP2A-PPP2R5C may also regulate the ERK signaling pathway through ERK dephosphorylation.[4] [5] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedProtein phosphatase 2A (PP2A) is a principal Ser/Thr phosphatase, the deregulation of which is associated with multiple human cancers, Alzheimer's disease and increased susceptibility to pathogen infections. How PP2A is structurally organized and functionally regulated remains unclear. Here we report the crystal structure of an AB'C heterotrimeric PP2A holoenzyme. The structure reveals that the HEAT repeats of the scaffold A subunit form a horseshoe-shaped fold, holding the catalytic C and regulatory B' subunits together on the same side. The regulatory B' subunit forms pseudo-HEAT repeats and interacts with the C subunit near the active site, thereby defining substrate specificity. The methylated carboxy-terminal tail of the C subunit interacts with a highly negatively charged region at the interface between A and B' subunits, suggesting that the C-terminal carboxyl methylation of the C subunit promotes B' subunit recruitment by neutralizing charge repulsion. Together, our structural results establish a crucial foundation for understanding PP2A assembly, substrate recruitment and regulation. Crystal structure of a protein phosphatase 2A heterotrimeric holoenzyme.,Cho US, Xu W Nature. 2007 Jan 4;445(7123):53-7. Epub 2006 Nov 1. PMID:17086192[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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