The Hydroxy/Aromatic Amino Acid Permease (HAAAP) Family
TC# 2.A.42
is a member of the large Amino Acid-Polyamine-OrganoCation (APC) Superfamily of secondary carrier proteins. Members of the HAAAP family all function in amino acid uptake. Homologues are present in a large number of

Gram-negative Gram-negative bacteria are bacteria that do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. They are characterized by their cell envelopes, which are composed of a thin peptidoglycan cell wall ...

and

Gram-positive bacteria In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. Gram-positive bact ...

, with at least one member classified from archaea
TC# 2.A.42.1.7
'' Thermococcus barophilus'')''.''

Structure

Proteins of the HAAAP family possess 403-443 amino acyl residues and exhibit eleven putative or established TransMembrane α-helical Spanners (TMSs). These proteins exhibit topological features common to the eukaryotic amino acid/auxin permease (AAAP) family
TC# 2.A.18
. These proteins also exhibit limited sequence similarity with some of the AAAP family members. A phylogenetic relationship has been proposed between members of the HAAAP family and APC family since they exhibit limited sequence similarity with one another. As of early 2016, there is no crystal structural data available for members of the HAAAP family in

RCSB The Protein Data Bank (PDB) is a database for the three-dimensional structural data of large biological molecules, such as proteins and nucleic acids. The data, typically obtained by X-ray crystallography, NMR spectroscopy, or, increasingly, cryo ...

Members

The HAAAP family includes three well-characterized aromatic amino acid/H⁺ symport permeases of ''E. coli'' and two hydroxy amino acid permeases. The aromatic amino acid/H⁺ symport permeases are: * Mtr, a high affinity tryptophan-specific permease
TC# 2.A.42.1.2
. * TnaB, a low affinity tryptophan permease
TC# 2.A.42.1.3
. * TyrP, a tyrosine-specific permease
TC# 2.A.42.1.1
. The two hydroxy amino acid permeases are: * SdaC, the serine permease
TC# 2.A.42.2.1
, of ''E. coli''. SdaC of ''E. coli'' (TC# 2.A.42.2.1) is also called DcrA, and together with a periplasmic protein DcrB (P37620), has been reported to play a role in phage DNA uptake in conjunction with an outer membrane receptors of the OMR family
TC# 1.B.14
. * TdcC, the threonine permease
TC# 2.A.42.2.2
, of ''E. coli''. Thus, FhuA
TC# 1.B.14.1.4
transports phage T5 DNA while BtuB
TC# 1.B.14.3.1
transports phage C1 DNA (Samsonov et al., 2002). DcuB is a putative

lipoprotein A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...

found only in enteric bacteria. All members of the HAAAP family can be found in th
Transporter Classification Database

Transport Reaction

The generalized transport reaction catalyzed by proteins of the HAAAP family is: Amino acid (out) + nH⁺ (out) → Amino acid (in) + nH⁺ (in).

References

{{Dual, source= Transporter Classification Database, sourcepath=http://www.tcdb.org/search/result.php?tc=2.A.42, sourcearticle=2.A.42 The Hydroxy/Aromatic Amino Acid Permease (HAAAP) Family, date=26 January 2016, authors(s)=Saier Lab Protein families Membrane proteins Transmembrane proteins Transmembrane transporters Transport proteins Integral membrane proteins