title: The PTR family: a new group of peptide transporters.
abstract: The transport of peptides into cells is a well-documented biological phenomenon which is accomplished by specific, energy-dependent transporters found in a number of organisms as diverse as bacteria and humans. Until recently, the majority of peptide transporters cloned and characterized were found to be proteins of the ATP-binding cassette (ABC) family. We report the identification of a new family of peptide transporters, which we call the PTR family. This group of proteins, distinct from the ABC-type peptide transporters, was uncovered by sequence analyses of a number of recently discovered peptide transport proteins. Alignment of these proteins demonstrated a high number of identical and similar residues and identified conserved glycosylation and phosphorylation sites, as well as a structural motif unique to this group of proteins. Cluster analysis among the proteins indicated these sequences were indeed related and could be further divided into two subfamilies. A phylogenetic analysis of these new peptide transport sequences, compared to over 50 other peptide and membrane-bound transporters, showed that these proteins comprise a distinct, separate group of proteins.
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D016384:Consensus Sequence; D017124:Conserved Sequence; D006031:Glycosylation; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000378:metabolism*; D010766:Phosphorylation; D010802:Phylogeny; D011499:Protein Processing, Post-Translational; D017386:Sequence Homology, Amino Acid
chemical_list: D002352:Carrier Proteins; D010455:Peptides