Nitrate transporters and peptide transporters.
In higher plants, two types of nitrate transporters, NRT1 and NRT2, have been identified. In Arabidopsis, there are 53 NRT1 genes and 7 NRT2 genes. NRT2 are high-affinity nitrate transporters, while most members of the NRT1 family are low-affinity nitrate transporters. The exception is CHL1 (AtNRT1.1), which is a dual-affinity nitrate transporter, its mode of action being switched by phosphorylation and dephosphorylation of threonine 101. Two of the NRT1 genes, CHL1 and AtNRT1.2, and two of the NRT2 genes, AtNRT2.1 and AtNRT2.2, are known to be involved in nitrate uptake. In addition, AtNRT1.4 is required for petiole nitrate storage. On the other hand, some members of the NRT1 family are dipeptide transporters, called PTRs, which transport a broad spectrum of di/tripeptides. In barley, HvPTR1, expressed in the plasma membrane of scutellar epithelial cells, is involved in mobilizing peptides, produced by hydrolysis of endosperm storage protein, to the developing embryo. In higher plants, there is another family of peptide transporters, called oligopeptide transporters (OPTs), which transport tetra/pentapeptides. In addition, some OPTs transport GSH, GSSH, GSH conjugates, phytochelatins, and metals.
Tsay
Yi-Fang
YF
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan. yftsay@gate.sinica.edu.tw
Chiu
Chi-Chou
CC
Tsai
Chyn-Bey
CB
Ho
Cheng-Hsun
CH
Hsu
Po-Kai
PK
D027321:Anion Transport Proteins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D017343:Genes, Plant; D005978:Glutathione / Q000378:metabolism; D007700:Kinetics; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000091285:Nitrate Transporters; D010802:Phylogeny; D054811:Phytochelatins; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D010944:Plants / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution
D027321:Anion Transport Proteins; D026901:Membrane Transport Proteins; D000091285:Nitrate Transporters; D010940:Plant Proteins; C043912:peptide permease; D054811:Phytochelatins; D005978:Glutathione