Journal article
Protein phosphatase 2A holoenzyme assembly: identification of contacts between B-family regulatory and scaffolding A subunits
The Journal of biological chemistry, Vol.277(23), pp.20750-20755
06/07/2002
DOI: 10.1074/jbc.M202992200
PMID: 11929880
Abstract
Protein serine/threonine phosphatase (PP) 2A is a ubiquitous enzyme with pleiotropic functions. Trimeric PP2A consists of a structural A subunit, a catalytic C subunit, and a variable regulatory subunit. Variable subunits (B, B', and B" families) dictate PP2A substrate specificity and subcellular localization. B-family subunits contain seven WD repeats predicted to fold into a beta-propeller structure. We carried out mutagenesis of Bgamma to identify domains important for association with A and C subunits in vivo. Several internal deletions in Bgamma abolished coimmunoprecipitation of A and C subunits expressed in COS-M6 cells. In contrast, small N- and C-terminal Bgamma deletions had no effect on incorporation into the PP2A heterotrimer. Thus, holoenzyme association of B-family subunits requires multiple, precisely aligned contacts within a core beta-propeller domain. Charge-reversal mutagenesis of Bgamma identified a cluster of conserved critical residues in Bgamma WD repeats 3 and 4. Acidic substitution of paired basic residues in Bgamma (RR165EE) abolished association with wild-type A and C subunits, while fostering incorporation of Bgamma into a PP2A heterotrimer containing an A subunit with an opposite charge-reversal mutation (EE100RR). Thus, binding of A and B subunits requires electrostatic interactions between conserved pairs of glutamates and arginines. By expressing complementary charge-reversal mutants in neuronal PC6-3 cells, we further show that holoenzyme incorporation protects Bgamma from rapid degradation by the ubiquitin/proteasome pathway.
Details
- Title: Subtitle
- Protein phosphatase 2A holoenzyme assembly: identification of contacts between B-family regulatory and scaffolding A subunits
- Creators
- Stefan Strack - Department of Pharmacology, University of Iowa, Iowa City, Iowa 52242, USA. stefan-strack@uiowa.eduRalf RuedigerGernot WalterRuben K DagdaChris A BarwaczJ Thomas Cribbs
- Resource Type
- Journal article
- Publication Details
- The Journal of biological chemistry, Vol.277(23), pp.20750-20755
- DOI
- 10.1074/jbc.M202992200
- PMID
- 11929880
- NLM abbreviation
- J Biol Chem
- ISSN
- 0021-9258
- eISSN
- 1083-351X
- Publisher
- United States
- Grant note
- DK25295 / NIDDK NIH HHS
- Language
- English
- Date published
- 06/07/2002
- Academic Unit
- Pathology; Iowa Neuroscience Institute; Neuroscience and Pharmacology; Family Dentistry; Ophthalmology and Visual Sciences
- Record Identifier
- 9984040360202771
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