InterPro domain: IPR013059

Amino acid permeases are integral membrane proteins involved in the transportof amino acids into the cell. A number of such proteins have been found to beevolutionary related [ 1 , 2 , 3 ].

Aromatic amino acids are concentrated in the cytoplasm of Escherichia coli by 4 distinct transport systems: a general aromatic amino acid permease, and aspecific permease for each of the 3 types (Phe, Tyr and Trp) [ 4 ]. It has been shown [ 5 ] that some permeases in E. coli and related bacteria are evolutionary related.These permeases are proteins of about 400 to 420 amino acids and are located in the cytoplasmic membrane and, like bacterial sugar/cation transporters, are thought to contain 12 transmembrane (TM)regions [ 6 ] - hydropathy analysis, however, is inconclusive, suggesting thepossibility of 10 to 12 membrane-spanning domains [ 6 ]. The best conserved domain is a stretch of 20 residues which seems to be located in a cytoplasmic loop between thefirst and second transmembrane region.

This family is specific for aromatic amino acid transporters and includes the tyrosine permease, TyrP ( P18199 ), and the tryptophan transporters TnaB ( P23173 ) and Mtr ( P22306 ) of E. coli.

1. Evolutionary relationship and secondary structure predictions in four transport proteins of Saccharomyces cerevisiae. J. Mol. Evol. 27, 341-50
2. Nucleotide sequence of the Saccharomyces cerevisiae PUT4 proline-permease-encoding gene: similarities between CAN1, HIP1 and PUT4 permeases. Gene 83, 153-9
3. Mammalian integral membrane receptors are homologous to facilitators and antiporters of yeast, fungi, and eubacteria. Protein Sci. 2, 20-30
4. Cloning, nucleotide sequence, and characterization of mtr, the structural gene for a tryptophan-specific permease of Escherichia coli K-12. J. Bacteriol. 173, 108-15
5. A new family of integral membrane proteins involved in transport of aromatic amino acids in Escherichia coli. J. Bacteriol. 173, 3231-4