title: Two conserved domains in regulatory B subunits mediate binding to the A subunit of protein phosphatase 2A.
abstract: Protein phosphatase 2A (PP2A) is an abundant heterotrimeric serine/threonine phosphatase containing highly conserved structural (A) and catalytic (C) subunits. Its diverse functions in the cell are determined by its association with a highly variable regulatory and targeting B subunit. At least three distinct gene families encoding B subunits are known: B/B55/CDC55, B'/B56/RTS1 and B"/PR72/130. No homology has been identified among the B families, and little is known about how these B subunits interact with the PP2A A and C subunits. In vitro expression of a series of B56alpha fragments identified two distinct domains that bound independently to the A subunit. Sequence alignment of these A subunit binding domains (ASBD) identified conserved residues in B/B55 and PR72 family members. The alignment successfully predicted domains in B55 and PR72 subunits that similarly bound to the PP2A A subunit. These results suggest that these B subunits share a common core structure and mode of interaction with the PP2A holoenzyme.
authors.affiliation: Department of Oncological Sciences, Center for Children, Huntsman Cancer Institute, University of Utah, Salt Lake City 84112, USA.
authors.forename: Xinghai
authors.initials: X
authors.lastname: Li
authors.forename: David M
authors.initials: DM
authors.lastname: Virshup
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D005982:Glutathione Transferase / Q000378:metabolism; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000737:chemistry / Q000378:metabolism*; D054648:Protein Phosphatase 2; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D011993:Recombinant Fusion Proteins; D005982:Glutathione Transferase; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2