Efflux Transporters
Efflux Transporters - Related Videos
07:47
A Proteoliposome-Based Efflux Assay to Determine Single-molecule Properties of Cl- Channels and Transporters
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Cited by 5 •
2015
Proteoliposomes are used to study purified channels and transporters reconstituted in a well-defined biochemical environment. An experimental procedure to measure efflux mediated by these proteins is illustrated. The steps to prepare proteoliposomes, perform the recordings, and analyze data to quantitatively determine the functional properties of the reconstituted protein are described.
05:22
Cancer Side Population Discrimination Assay: A Method to Isolate Cancer Stem-like Cells Using Hoechst Dye Efflux Assay
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2023
In this video, we describe the isolation of a subpopulation of cancer stem-like cells from head and neck squamous carcinoma cell lines using fluorescence-activated cell sorter or FACS. The isolated side population of cells can be used for further downstream analysis.
07:54
Cholesterol Efflux Assay
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Cited by 74 •
2012
The cholesterol assay is designed to quantitate the rate of cholesterol efflux from cultured cells and the capacity of plasma acceptors to accept cholesterol released from cells. The assay consists of labelling cells with cholesterol, equilibration of cholesterol among intracellular pools and release of cholesterol to an extracellular acceptor.
13:40
In vitro Investigation of the MexAB Efflux Pump From Pseudomonas aeruginosa
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Cited by 11 •
2014
We present a protocol for the in vitro investigation of efflux pumps from Pseudomonas aeruginosa. This protocol allows for the generation of a robust, reversible, and tunable proton gradient within the liposome membrane and hence should be adaptable to any membrane protein energized by the protomotive force.
05:06
Characterizing Multidrug Efflux Systems in Acinetobacter baumannii Using an Efflux-Deficient Bacterial Strain and a Single-Copy Gene Expression System
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Cited by 1 •
2024
We describe a facile procedure for the single-copy chromosomal complementation of an efflux pump gene using a mini-Tn7-based expression system into an engineered efflux-deficient strain of Acinetobacter baumannii. This precise genetic tool allows for controlled gene expression, which is key for the characterization of efflux pumps in multidrug resistant pathogens.
FAQs
ATP-binding cassette transporters use energy released when ATP is hydrolyzed to drive compound export. Solute carrier systems can instead couple transport to electrochemical gradients. Because these mechanisms rely on different driving forces, their activity may respond to different cellular conditions, producing distinct effects on intracellular drug concentrations and tissue exposure.
For solute carrier systems, electrochemical gradients can supply the force needed to move compounds out of cells. The resulting transport depends on the gradient across the membrane rather than directly on ATP hydrolysis. This mechanism helps determine how efficiently a drug or metabolite leaves a cell and therefore influences the concentration available for cellular action.
Inhibition can reduce transporter-mediated export, allowing more compound to remain inside cells or reach tissues. Induction can increase export and limit intracellular or tissue exposure. These opposing changes can alter absorption, distribution, metabolism, and excretion, making transporter activity an important source of clinical drug interactions when medicines affect one another's transporter function.
The intestine, liver, kidneys, and blood-brain barrier are key sites for evaluating transporter effects. Activity in these locations can influence how much drug is absorbed, distributed into tissues, processed, or eliminated. Considering all four sites helps connect cellular export with the overall pharmacokinetic profile and with differences in exposure between circulating blood and protected tissues.
Efflux transporter activity at the blood-brain barrier can limit the amount of a drug that reaches the brain. This protective export contributes to tissue regulation but may also restrict therapeutic exposure in the central nervous system. Changes in transporter function, including inhibition or induction, can therefore modify the distribution of medicines into this protected compartment.
Enhanced export can lower intracellular concentrations of drugs, reducing the exposure available to produce a therapeutic effect. When this mechanism affects several compounds, it can contribute to multidrug resistance. The same principle also explains why transporter activity matters in clinical pharmacology: excessive export may limit treatment response, while altered activity can change susceptibility to drug interactions.