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Related Concept Videos

Membrane Transporters01:31

Membrane Transporters

Transporters are essential membrane transport proteins with functions related to cell nutrition, homeostasis, communication, etc. Approximately 7% of all genes in the human genome code for transporters or transporter-related proteins.
Transporters are mainly composed of alpha-helices, built from bundles of ten or more helices traversing the plasma membrane. The solute-binding sites are located midway, where some of the helices are broken or distorted, making space for the binding site through...
Facilitated Diffusion01:16

Facilitated Diffusion

The plasma membrane, a critical structure in cellular biology, houses an array of transporters, or carrier proteins, interspersed within its lipid bilayer. These proteins play a crucial role in solute transport through facilitated diffusion, a form of passive diffusion that uses transporters to move the molecules across the membrane.
In this process, substrates such as organic compounds and ions interact with a transporter on one side, triggering conformational changes in proteins that enable...
The Significance of Membrane Transport01:44

The Significance of Membrane Transport

The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
The Significance of Membrane Transport01:44

The Significance of Membrane Transport

The transport of solutes across the cell membrane is essential for metabolic processes, like maintaining cell size and volume, generating the action potential, exchanging nutrients and gases, etc. Membrane transport can be either passive or active. It can be simple diffusion, facilitated, or mediated transport aided by transport proteins such as transporters and channels.
Transporters facilitate either an active or passive movement of solutes. They can allow a single-molecule transport down its...
Facilitated Transport01:19

Facilitated Transport

The chemical and physical properties of plasma membranes cause them to be selectively permeable. Since plasma membranes have both hydrophobic and hydrophilic regions, substances need to be able to transverse both regions. The hydrophobic area of membranes repels substances such as charged ions. Therefore, such substances need special membrane proteins to cross a membrane successfully. In  facilitated transport, also known as facilitated diffusion, molecules and ions travel across a membrane via...
Facilitated Transport01:19

Facilitated Transport

The chemical and physical properties of plasma membranes cause them to be selectively permeable. Since plasma membranes have both hydrophobic and hydrophilic regions, substances need to be able to transverse both regions. The hydrophobic area of membranes repels substances such as charged ions. Therefore, such substances need special membrane proteins to cross a membrane successfully. In facilitated transport, also known as facilitated diffusion, molecules and ions travel across a membrane via...

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Related Experiment Video

Updated: Jul 19, 2026

High-Throughput Expression and Purification of Human Solute Carriers for Structural and Biochemical Studies
07:10

High-Throughput Expression and Purification of Human Solute Carriers for Structural and Biochemical Studies

Published on: September 29, 2023

Transporters as channels.

Louis J DeFelice1, Tapasree Goswami

  • 1Department of Pharmacology and Molecular Neuroscience, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA. lou.defelice@vanderbilt.edu

Annual Review of Physiology
|October 25, 2006
PubMed
Summary

This review explores transporter channels, challenging traditional alternating access models. Recent evidence directly and indirectly shows channel properties in transporters, prompting new questions about their biological significance.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Transport

Background:

  • The alternating access model is the prevailing theory for cotransport mechanisms.
  • This model posits large conformational changes in transporter proteins during transport.
  • Decades of research have supported the alternating access model due to its explanatory power.

Purpose of the Study:

  • To review recent data on the channel properties of transporter proteins.
  • To discuss evidence for the existence of channels within transporters.
  • To explore the potential biological significance of these channel properties.

Main Methods:

  • Review of recent experimental data, including direct observation of single-transporter currents.
  • Analysis of indirect evidence, such as fluctuation analysis and large transporter currents.

More Related Videos

Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters
11:51

Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters

Published on: February 3, 2018

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
13:16

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles

Published on: December 31, 2019

Related Experiment Videos

Last Updated: Jul 19, 2026

High-Throughput Expression and Purification of Human Solute Carriers for Structural and Biochemical Studies
07:10

High-Throughput Expression and Purification of Human Solute Carriers for Structural and Biochemical Studies

Published on: September 29, 2023

Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters
11:51

Application of Electrophysiology Measurement to Study the Activity of Electro-Neutral Transporters

Published on: February 3, 2018

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles
13:16

Characterization of Membrane Transporters by Heterologous Expression in E. coli and Production of Membrane Vesicles

Published on: December 31, 2019

  • Examination of ion channel theory and cotransport physiology for background context.

    • Main Results:

    • New experimental findings reveal the existence of channel-like structures within transporters.
    • Direct evidence includes the observation of single-transporter currents.
    • Indirect evidence supports channel properties through fluctuation analysis and current measurements.

    Conclusions:

    • The existence of channels in transporters is experimentally supported.
    • The functional and biological significance of these channel properties remains largely unknown.
    • Further research is needed to understand this newly identified aspect of transport proteins.