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Title: Identification and functional analysis of two Ca2+-binding EF-hand motifs in the B"/PR72 subunit of protein phosphatase 2A
Authors: Janssens, Veerle ×
Jordens, Jan
Stevens, Ilse
Van Hoof, Christine
Martens, Ellen
De Smedt, Humbert
Engelborghs, Yves
Waelkens, Etienne
Goris, Jozef #
Issue Date: Mar-2003
Series Title: Journal of Biological Chemistry vol:278 issue:12 pages:10697-706
Abstract: Protein phosphatase 2A (PP2A) is a multifunctional serine/threonine phosphatase that is critical to many cellular processes including cell cycle regulation and signal transduction. PP2A is a heterotrimer containing a structural (A) and catalytic (C) subunit, associated with one variable regulatory or targeting B-type subunit, of which three families have been described to date (B/PR55, B'/PR61, and B"/PR72). We identified two functional and highly conserved Ca(2+)-binding EF-hand motifs in human B"/PR72 (denoted EF1 and EF2), demonstrating for the first time the ability of Ca(2+) to interact directly with and regulate PP2A. EF1 and EF2 apparently bind Ca(2+) with different affinities. Ca(2+) induces a significant conformational change, which is dependent on the integrity of the motifs. We have further evaluated the effects of Ca(2+) on subunit composition, subcellular targeting, catalytic activity, and function during the cell cycle of a PR72-containing PP2A trimer (PP2A(T72)) by site-directed mutagenesis of either or both motifs. The results suggest that integrity of EF2 is required for A/PR65 subunit interaction and proper nuclear targeting of PR72, whereas EF1 might mediate the effects of Ca(2+) on PP2A(T72) activity in vitro and is at least partially required for the ability of PR72 to alter cell cycle progression upon forced expression.
ISSN: 0021-9258
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Biochemistry Section (Medicine) (-)
Faculty of Medicine - miscellaneous
Biochemistry, Molecular and Structural Biology Section
Laboratory of Molecular and Cellular Signaling
Laboratory of Protein Phosphorylation and Proteomics
Faculty of Pharmaceutical Sciences - miscellaneous
Laboratory of Phosphoproteomics (-)
× corresponding author
# (joint) last author

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