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 carriers. Members of the HAAAP family all function in amino acid uptake. Homologues are present in a large number of Gram-negative and Gram-positive bacteria  . Structure These proteins 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) , and they exhibit limited sequence similarity with some of them. Since members of the HAAAP family  exhibit limited sequence similarity with the large APC family (TC# 2.A.3), there is most likely a phylogenetic relationship between members of both families. As of early 2016, no crystal structures of members of the HAAAP family can be found on RCSB. Members of the HAAAP Family The HAAAP family includes three well-characterized aromatic amino acid:H+ symport permeases of E. coli: a high affinity tryptophan-specific permease, Mtr (TC# 2.A.42.1.2), a low affinity tryptophan permease, TnaB (TC# 2.A.42.1.3), and a tyrosine-specific permease, TyrP (TC# 2.A.42.1.1), as well as two well-characterized hydroxy amino acid permeases, the serine permease, SdaC (TC# 2.A.42.2.1), of E. coli, and the threonine permease, TdcC (TC# 2.A.42.2.2), of E. coli . Other proteins also included in the HAAAP family can be found in the Transporter Classification Database .
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 carriers. Members of the HAAAP family all function in amino acid uptake. Homologues are present in a large number of Gram-negative and Gram-positive bacteria , 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. Members of the HAAAP Family The HAAAP family includes three well-characterized aromatic amino acid:H+ symport permeases of E. coli: a high affinity tryptophan-specific permease, Mtr (TC# 2.A.42.1.2), a low affinity tryptophan permease, TnaB (TC# 2.A.42.1.3), and a tyrosine-specific permease, TyrP (TC# 2.A.42.1.1), as well as two well-characterized hydroxy amino acid permeases, the serine permease, SdaC (TC# 2.A.42.2.1), of E. coli, and the threonine permease, TdcC (TC# 2.A.42.2.2), of E. coli .
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, with at least one member classified from archaea (TC# 2.A.42.1.7, Thermococcus barophilus)
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These proteins
Proteins of the HAAAP family
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, and they
. These proteins also
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them. Since
the AAAP family members. A phylogenetic relationship has been proposed between
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and APC family since they
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the large APC family (TC# 2.A.3), there is most likely a phylogenetic relationship between members of both families.
one another.
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no crystal structures of
there is no crystal structural data available for
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can be found on
in
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. Other proteins also included in the HAAAP family can be found in the Transporter Classification Database