Transporter targets

Research beyond ion channels.

Transporters: The Future of Medicine

Membrane transporters are increasingly being recognized as important players in human health and disease. SLC transporters make the majority of human transport proteins, followed by ion channels and pumps. With their function still being discovered, many SLC transporters have been promising drug targets for diseases such as diabetes, cancer, neurological disorders (epilepsy, Parkinson’s, and Alzheimer’s) and immunological disorders, cardiovascular and metabolic diseases. In addition, some transporters function as drug transporters and also play a crucial role in pharmacokinetics and how a potential drug is distributed in the human body.

Diversity of Membrane Transporters

Functional and Phylogenetic Classification

Across all species, transport proteins are organized into three major classes according to their energy coupling mechanisms: channels, pumps, and transporters according to the Transport Classification (TC) system. It is the most comprehensive system to appreciate the number and diversity of membrane transport proteins. In contrast to ion channels, transporters have more diverse substrates (amino acids, sugars, and other metabolites, neurotransmitters, vitamins, cofactors, and transition metals), in addition to their various modes of action.

Channels mediate substrate translocation through passive flux along their electrochemical gradient. Pumps are primary active transport proteins, using a primary energy source such as ATP or light to mediate substrate flux. Except for uniporters, transporters are secondary active transport proteins, coupling the flux of one substrate along its electrochemical gradient to drive the transport of another substrate against its electrochemical gradient. Translocation of the two substrates may occur in the same direction (cotransporter or symporter) or in opposite directions (antiporter or exchanger).


Transporters have diverse substrates, as well as mechanisms of action. After substrate binding, transporters undergo multiple conformational transitions, allowing for alternating access of the substrate binding sites to either side of the membrane. These transitions involve mechanisms such as rocker-switch movements, gated pores, or elevators, that switch between outward- and inward-facing transporter states. Adding substrate-bound and -free states and often additional high and low-energy transporter intermediates, typical ‘simplified’ transport cycles consist of four to ten states. Given specific rate constants for substrate binding and release steps and all subsequent transitions, transport cycles are way more complicated to study.

SURFE2R technology

Automated Transporter Measurements

Most transport proteins are accessible using our SURFE2R technology, specifically all types of electrogenic transporters (symporters, exchangers, uniporters), ligand-gated and leak channels, and ATPases.

The SURFE2R uses capacitive sensors and is not able to perform voltage steps to trigger ion translocation but uses a perfusion system to provide substrate gradients. The SURFE2R technology clearly differentiates from patch clamp through the measurement of substrate-induced currents making pre-steady-state kinetics of substrate binding accessible. For this reason, patch clamp technology would be a better choice if voltage-gated ion channels are in focus.

On the other hand, the SURFE2R allows measuring slow transporters and transporters from intracellular membranes, both of which are usually hardly accessible via patch clamp technology. The SURFE2R 96SE allows for drug screening on transporters in a 96-sensor well format, while the SURFE2R N1 was designed for its high assay flexibility and is easy to use.

How can we help you?

Contact our specialist Dr. Maria Barthmes (Product Manager of the SURFE2R product family). Maria is delighted to help you:
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