The PTR family: a new group of peptide transporters

Mol Microbiol. 1995 Jun;16(5):825-34. doi: 10.1111/j.1365-2958.1995.tb02310.x.


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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Bacteria / metabolism
  • Carrier Proteins / chemistry*
  • Carrier Proteins / metabolism*
  • Cell Membrane / metabolism
  • Consensus Sequence
  • Conserved Sequence
  • Glycosylation
  • Humans
  • Molecular Sequence Data
  • Peptides / metabolism*
  • Phosphorylation
  • Phylogeny*
  • Protein Processing, Post-Translational
  • Sequence Homology, Amino Acid


  • Carrier Proteins
  • Peptides

Associated data