Characterization of the Protein Phosphatase 2A Regulatory Subunit PR70
type: CreativeWork
description: Protein phosphatase 2A (PP2A) is a phosphoserine/threonine phosphatase that controls the phosphorylation of numerous proteins in eukaryotic cells. PP2A consists of a core dimer composed of a scaffolding subunit (A-subunit) and a catalytic subunit (C-subunit) that interacts with a variety of regulatory subunits. There are four families of regulatory subunits: R2, R3, R4, and R5. The diversity of regulatory subunits gives rise to multiple PP2A holoenzymes and accounts for the ability of PP2A to regulate diverse cellular processes. Relatively little is known about the molecular basis for the interaction of the regulatory subunits with the core dimer and substrates. A more thorough understanding of these interactions would provide insights into how the regulatory subunits target PP2A to different cellular processes. The R3 regulatory subunit termed PR70 was identified in a yeast two hybrid screen with the DNA replication protein Cdc6 as bait. PR70 interacts with the PP2A core dimer and Cdc6 in vivo and in vitro. Biochemical approaches were used to identify regions and residues within PR70 that are important for mediating protein-protein interactions with the PP2A core dimer and Cdc6. PR70 contains two conserved calcium binding EF hand motifs and binds calcium in vitro. Calcium enhances the binding of PR70 to the A-subunit but not to Cdc6. Although calcium did not enhance the binding of PR70 to Cdc6, it did result in an increase in the amount of PP2A associated with Cdc6. Both calcium binding and enhanced interactions with the A-subunit require functional EF hand motifs. A conserved motif within the conserved R3 family domain was identified that is sufficient for the interaction of PR70 with PP2A. The C-terminal region was shown to be important for the interaction of PR70 with Cdc6, but not with the A-subunit. This result suggested that different portions of PR70 are important for mediating interactions with PP2A and Cdc6. Finally, PR70 is phosphorylated in intact cells …
abstract: Protein phosphatase 2A (PP2A) is a phosphoserine/threonine phosphatase that controls the phosphorylation of numerous proteins in eukaryotic cells. PP2A consists of a core dimer composed of a scaffolding subunit (A-subunit) and a catalytic subunit (C-subunit) that interacts with a variety of regulatory subunits. There are four families of regulatory subunits: R2, R3, R4, and R5. The diversity of regulatory subunits gives rise to multiple PP2A holoenzymes and accounts for the ability of PP2A to regulate diverse cellular processes. Relatively little is known about the molecular basis for the interaction of the regulatory subunits with the core dimer and substrates. A more thorough understanding of these interactions would provide insights into how the regulatory subunits target PP2A to different cellular processes. The R3 regulatory subunit termed PR70 was identified in a yeast two hybrid screen with the DNA replication protein Cdc6 as bait. PR70 interacts with the PP2A core dimer and Cdc6 in vivo and in vitro. Biochemical approaches were used to identify regions and residues within PR70 that are important for mediating protein-protein interactions with the PP2A core dimer and Cdc6. PR70 contains two conserved calcium binding EF hand motifs and binds calcium in vitro. Calcium enhances the binding of PR70 to the A-subunit but not to Cdc6. Although calcium did not enhance the binding of PR70 to Cdc6, it did result in an increase in the amount of PP2A associated with Cdc6. Both calcium binding and enhanced interactions with the A-subunit require functional EF hand motifs. A conserved motif within the conserved R3 family domain was identified that is sufficient for the interaction of PR70 with PP2A. The C-terminal region was shown to be important for the interaction of PR70 with Cdc6, but not with the A-subunit. This result suggested that different portions of PR70 are important for mediating interactions with PP2A and Cdc6. Finally, PR70 is phosphorylated in intact cells …
author: Davis, Anthony John
language: en
keywords: Protein Phosphatase 2A, Phosphorylation, Yeast Two Hybrid System Techniques
date published: 2010-07-12T18:39:30Z
date modified: 2026-07-24T05:52:29Z
provider: University of Texas Southwestern Medical Center
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of Texas Southwestern Medical Center

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2152.5/632