4-hydroxybenzoate transporter PcaK and similar transporters of the Major Facilitator Superfamily
This aromatic acid:H(+) symporter subfamily includes Acinetobacter sp. 4-hydroxybenzoate transporter PcaK, Pseudomonas putida gallate transporter (GalT), Corynebacterium glutamicum gentisate transporter (GenK), Nocardioides sp. 1-hydroxy-2-naphthoate transporter (PhdT), Escherichia coli 3-(3-hydroxy-phenyl)propionate (3HPP) transporter (MhpT), and similar proteins. These transporters are involved in the uptake across the cytoplasmic membrane of specific aromatic compounds such as 4-hydroxybenzoate, gallate, gentisate (2,5-dihydroxybenzoate), 1-hydroxy-2-naphthoate, and 3HPP, respectively. The PcaK-like aromatic acid:H(+) symporter subfamily belongs to the Metazoan Synaptic Vesicle Glycoprotein 2 (SV2) and related small molecule transporter family (SV2-like) of the Major Facilitator Superfamily (MFS) of membrane transport proteins. MFS proteins are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",