ABSTRACT
Peptide transport systems mediate the uptake of small peptides across the plasma membrane into the cell cytoplasm. These systems are present in bacteria, fungi, plants, and animals. Transport of peptides is accomplished by a specific biochemical process in which peptides (<6 amino acids) are transported by energy-dependent, saturable carriers. Peptide transport systems mediate the uptake of small peptides across the plasma membrane into the cell cytoplasm. This chapter reports the characterization of two plant peptide transport genes, AtPTR2-A and AtPTR2-B isolated by expressing an Arabidopsis cDNA library in the yeast peptide transport mutant ptrl. The cloning of two plant peptide transport genes is consistent with previous reports identifying at least two and possibly three proteins associated with peptide transport in barley grains. Isolation of the plant peptide transport genes also brings about the possibility of exploiting this system for delivery of toxic or growth promoting substances to plants in a manner analogous to that postulated for human pathogens.
