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Ion channels

Ion channels are transmembrane proteins specialised in the fine control of the passive flow of naturally occurring ions (Sodium, Chloride, Potassium, and Calcium). They play crucial roles in living cells, from initiating and facilitating propagation of electrical signals across membranes to regulating cell volume. They are so important that they rank as the second most important target for the development of pharmaceutical drugs, yet the basis of ion transportation is still not completely understood, and recent finding shed a light on the involvement of non-trivial quantum effects on the mechanisms underlying this process. Improving our comprehension of ion transportation will be key to ameliorate our understanding of the very essence of cellular homeostasis and communication.

Overview

Properties central to the functionality of many ion channels are ion selectivity and ion conduction. Ion selectivity is conferred by a portion of the protein known as the selectivity filter; these filters provide the ability to discriminate between different ions due to its diameter (of a few angstroms) and highly conserved motifs of residues that pull ions within the pore thanks to the attractive force of Coulomb interactions. This ensures that ions proceed through the channel in a single file fashion without their hydration shell. Ion conduction on the other hand, is regulated by a specialised segment known as the voltage-sensing domain that can modify the opening state of the whole protein in response to a change of voltage in the membrane.

Both selectivity and conduction have been recently proposed to be influenced by quantum coherence and quantum interference. Indeed, many ion channels display remarkable values of conduction and selectivity that cannot be successfully explained by current models, as in the case of bacterial voltage-gated potassium channel KcsA, combining very high throughput rates (108 ions/sec.), close to the diffusion limit, with a high discrimination rate between potassium and sodium (104:1), despite of the low difference between the Potassium and Sodium atomic radius (0.38 Å).

Here at the QB-DTC we will use different techniques and models to test the hypothesis that non-trivial quantum effects are required for a satisfactory comprehension of the mechanisms underlying ion transportation.

Research team

Brendan Howlin profile image

Professor Brendan Howlin

Professor of Computational Chemistry

Kamalan Jeevaratnam profile image

Dr Kamalan Jeevaratnam

Associate Dean International FHMS, Head of Department (Veterinary Preclinical Sciences), Reader in Clinical Physiology

Rebecca Lewis profile image

Dr Rebecca Lewis

Lecturer in Physiology

Johnjoe McFadden profile image

Professor Johnjoe McFadden

Professor of Molecular Genetics, Associate Dean (International)

S. Ravi P. Silva profile image

Professor Ravi Silva

Director, Advanced Technology Institute (ATI) and Head of NanoElectronics Centre

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Leverhulme Quantum Biology Doctoral Training Centre (QB-DTC)
Robert Boyle (AZ) Building
University of Surrey
Guildford
Surrey
GU2 7XH