title: Enigma variations for peptides and their transporters in higher plants.
abstract: BACKGROUND
  Two families of proteins that transport small peptides, the oligopeptide transporters (OPTs) and the peptide transporters (PTRs), have been recognized in eukaryotes. Higher plants contain a far greater number of genes for these transporters than do other eukaryotes. This may be indicative of the relative importance of (oligo)peptides and their transport to plant growth and metabolism.
  
  
  RESULTS
  Recent studies are now allowing us to assign functions to these transporters and are starting to identify their in-planta substrates, revealing unexpected and important contributions of the transporters to plant growth and developmental processes. This Botanical Briefing appraises recent findings that PTRs and OPTs have key roles to play in the control of plant cell growth and development. Evidence is presented that some of these transporters have functions outside that of nitrogen nutrition and that these carriers can also surprise us with their totally unexpected choice of substrates.
authors.affiliation: Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK.
authors.forename: Wanda M
authors.initials: WM
authors.lastname: Waterworth
authors.forename: Clifford M
authors.initials: CM
authors.lastname: Bray
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000145:classification / Q000378:metabolism / Q000502:physiology; D026901:Membrane Transport Proteins / Q000145:classification / Q000378:metabolism* / Q000502:physiology; D005810:Multigene Family; D009842:Oligopeptides / Q000378:metabolism*; D010455:Peptides / Q000378:metabolism; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000378:metabolism* / Q000502:physiology; D010944:Plants / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D029681:Arabidopsis Proteins; D026901:Membrane Transport Proteins; D009842:Oligopeptides; D010455:Peptides; D010940:Plant Proteins