title: PII in higher plants: a modern role for an ancient protein.
abstract: PII in prokaryotic organisms is a crucial integrator of cellular carbon, nitrogen and energy levels. In higher plants, however, its role remains significantly less clear. Previous findings suggest that PII-N-acetylglutamate kinase (NAGK) complex formation controls l-arginine biosynthesis, whereas other work implicates PII in regulating chloroplastic NO2(-) uptake. Together, these findings indicate that PII has evolved from a central metabolic role in prokaryotes towards a more specialized role in eukaryotes. Furthermore, recent genomic and bioinformatic findings reveal tissue-specific expression of PII in higher plants, with transcriptional expression patterns suggestive of a link between PII and storage protein production during seed development. This review focuses on the unique structural, biochemical and biological aspects of PII in higher plants.
authors.affiliation: Department of Biological Sciences, University of Calgary, Calgary, AB, Canada T2N1N4.
authors.forename: R Glen
authors.initials: RG
authors.lastname: Uhrig
authors.forename: Kenneth K S
authors.initials: KK
authors.lastname: Ng
authors.forename: Greg B G
authors.initials: GB
authors.lastname: Moorhead
mesh_terms: D017124:Conserved Sequence; D009928:Organ Specificity; D051922:PII Nitrogen Regulatory Proteins / Q000737:chemistry / Q000378:metabolism*; D017851:Phosphotransferases (Carboxyl Group Acceptor) / Q000378:metabolism; D059828:Plant Cells; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D010944:Plants / Q000201:enzymology / Q000378:metabolism*
chemical_list: D051922:PII Nitrogen Regulatory Proteins; D010940:Plant Proteins; D017851:Phosphotransferases (Carboxyl Group Acceptor); C018721:acetylglutamate kinase