title: Diversity in subcellular targeting of the PP2A B'eta subfamily members.
abstract: Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase comprising a catalytic subunit (C), a scaffolding subunit (A), and a regulatory subunit (B). The B subunits are believed to be responsible for substrate specificity and localization of the PP2A complex. In plants, three families of B subunits exist, i.e. B (B55), B', and B''. Here, we report differential subcellular targeting within the Arabidopsis B'eta subfamily, which consists of the close homologs B'eta, B'theta, B'gamma and B'zeta. Phenotypes of corresponding knockouts were observed, and particularly revealed delayed flowering for the B'eta knockout. The B' subunits were linked to fluorescent tags and transiently expressed in various tissues of onion, tobacco and Arabidopsis. B'eta and B'gamma targeted the cytosol and nucleus. B'zeta localized to the cytoplasm and partly co-localized with mitochondrial markers when the N-terminus was free. Provided its C-terminus was free, the B'theta subunit targeted peroxisomes. The importance of the C-terminal end for peroxisomal targeting was further confirmed by truncation of the C-terminus. The results revealed that the closely related B' subunits are targeting different organelles in plants, and exemplify the usage of the peptide serine-serine-leucine as a PTS1 peroxisomal signaling peptide.
authors: Faculty of Science and Technology, University of Stavanger, Centre for Organelle Research, 4036 Stavanger, Norway.
authors: Polina
authors: P
authors: Matre
authors: Christian
authors: C
authors: Meyer
authors: Cathrine
authors: C
authors: Lillo
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000201:enzymology*; D002466:Cell Nucleolus / Q000201:enzymology; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology; D008969:Molecular Sequence Data; D009928:Organ Specificity; D020675:Peroxisomes / Q000201:enzymology; D054648:Protein Phosphatase 2 / Q000737:chemistry / Q000378:metabolism*; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016415:Sequence Alignment; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D011993:Recombinant Fusion Proteins; D054648:Protein Phosphatase 2