Molecular mechanisms of urea transport in plants.
Urea is a soil nitrogen form available to plant roots and a secondary nitrogen metabolite liberated in plant cells. Based on growth complementation of yeast mutants and "in-silico analysis", two plant families have been identified and partially characterized that mediate membrane transport of urea in heterologous expression systems. AtDUR3 is a single Arabidopsis gene belonging to the sodium solute symporter family that cotransports urea with protons at high affinity, while members of the tonoplast intrinsic protein (TIP) subfamily of aquaporins transport urea in a channel-like manner. The following review summarizes current knowledge on the membrane localization, energetization and regulation of these two types of urea transporters and discusses their possible physiological roles in planta.
Kojima
S
S
Institut für Pflanzenernährung (330), Universität Hohenheim, Fruwirthstrasse 20, 70599, Stuttgart, Germany.
Bohner
A
A
von Wirén
N
N
D029681:Arabidopsis Proteins / Q000378:metabolism*; D001693:Biological Transport, Active / Q000502:physiology; D008565:Membrane Proteins / Q000378:metabolism*; D008954:Models, Biological; D010940:Plant Proteins / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D027981:Symporters / Q000378:metabolism*; D014508:Urea / Q000378:metabolism*
D029681:Arabidopsis Proteins; C474639:DUR3 protein, Arabidopsis; D008565:Membrane Proteins; D010940:Plant Proteins; D027981:Symporters; D014508:Urea