Yeast Polyamine transporter 1 (Tpo1) and similar multidrug resistance (MDR) transporters of the Major Facilitator Superfamily
This family is composed of fungal multidrug resistance (MDR) transporters including several proteins from Saccharomyces cerevisiae such as polyamine transporters 1-4 (Tpo1-4), quinidine resistance proteins 1-3 (Qdr1-3), dityrosine transporter 1 (Dtr1), fluconazole resistance protein 1 (Flr1), and protein HOL1. MDR transporters are drug/H+ antiporters (DHA) that mediate the efflux of a variety of drugs and toxic compounds, and confer resistance to these compounds. For example, Flr1 confers resistance to the azole derivative fluconazole while Tpo1 confers resistance and adaptation to quinidine and ketoconazole. The polyamine transporters are involved in the detoxification of excess polyamines in the cytoplasm. Tpo1-like MDR transporters belong to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which 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.",