Ion channels are macromolecular protein structures which form pores within the membrane of cells to enable the movement of ions into and out of cells, and is the basis of fundamental process such as establishing a resting potential, generation of action potentials etc. In order for the channel to be involved in these cell functions it must possess certain features such as ionic specificity, gating mechanism (i.e. voltage or ligand binding), for these reasons, channels have been the subject of much research over the past few decades.
All ion channels are described as having 2 common functional properties, a selective filter which determines the specificity of the channel and a gate which opens under specific conditions; in addition, these channels can be classified into 2 groups depending of the type of gating mechanism, i.e. voltage or ligand gated. {{Hucho,Ferdinand 2001}}
Ligand-gated ion channels, (which is the focus of this essay) are activated when a certain ligand(s) bind to an extracellular binding site causing the receptor to undergo a conformational change, resulting in the opening of the pore, thus ion flow through, down the electrochemical gradient.
The term ligand gated ion channel (LGIC) is a general term used to describe 3 ‘superfamilies’ of ion channels; Cysteine-loop receptors, Ionotropic Glutamate receptors (IGluR) and ATP-gated ion channels. All these superfamiles can be further split into families of receptors.
Members of a superfamily differ from member of a family. The term family is used to describe receptors that are similar in structure as they are coded for by similar genes, whereas superfamilies are different from each other in structure and function, but evolves from a common ancestor, thus they mu...
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...em.2011 Mar;116(5):734-41.Doi: 10.1111/j.1471-4159.2010.07060.x.Epub 2011 Jan 13.
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A representation of P2X subunit structure and function. (n.d.). Retrieved December 4, 2013, from Nature: http://www.nature.com/nrn/journal/v2/n3/fig_tab/nrn0301_165a_F2.html
Cys-loop receptor channel structure . (n.d.). Retrieved December 4, 2013, from Nature: http://www.nature.com/nchembio/journal/v8/n12/fig_tab/nchembio.1115_F1.html
Glutamate Receptors . (n.d.). Retrieved December 4, 2013, from University of Bristol: http://www.bris.ac.uk/synaptic/receptors/
Rang, H. P., Dale, M. M., Ritter, J. M., Flower, R. J., & Henderson, G. (2012). Pharmacology (7 ed.). London: Elsevier Inc.
Dr. Akabas ended his paper with a summary of his results. He concluded that Gly-91, Lys-95, and Gln-98 all line the CFTR channel and are arranged in a helical formation. Dr. Akabas also talked about the problems and surprises he faced during his experiment, such as a missense mutation of Gly-91 to Arg. In the end, substituted-cysteine-accessibility method exceeded the expectations of many and contributed greatly to our knowledge of the CFTR channel. Even though more research and discovery is being done today, we will always remember Dr. Akabas’s experiment as being the basis of the CFTR science.
The pump exchanges three sodium molecules for two potassium molecules. In doing so an electrical gradient is formed across the basolateral membrane of the cell due to the imbalance of charge generated. The interior of the cell is negative by about 80mV in relation to the outside...
However, the exact mechanism of action of Levetiracetam (LEV) is not currently understood and the anticonvulsant characteristics of LEV are different than other antiepileptic drugs (AEDs) (2). For instance, LEV does not present the ability to inhibit sodium channels or enhance g-aminobutyric acid (GABA) function like several other AEDs (1). The understanding of the mechanism of action of LEV as an AED is important to understand the cellular mechanisms and pathogenesis of epilepsy and develop new methods of treating epilepsy. Past studies have shown LEV to target high-voltage-activated (HVA) N-type calcium (Ca2+) channels, the synaptic vesicle protein 2A (SV2A), and inhibit inositol 1,4,5-triphosphate receptors (IP3R) and ryanodine receptors (RyR) activated calcium-induced calcium release (CICR) (1)(3)(4).
There are a series of nodes along the axon where there is a high concentration of sodium (Na+) and K+ channels. There is a high concentration of Na+ outside the cell and a high concentration of K+ inside the cell. As the nodes sen...
Its ability to inhibit sodium channels within brain cells thereby protecting the cells from hypoxia (lack of oxygen)
glutamate receptors using antibodies, that tag on to the receptor itself. The proteins that make up the
problems within the specific ion channels known to cause the disease. The goal of the
γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the CNS. GABAA is a ligand gated ion channel composed of five subunits. Through positive allosteric modulation ethanol binds to the δ subunit of the receptor and enhances the inhibitory effect of GABA. Once ethanol has bound to the GABAA receptor, chloride ions enter the post-synaptic neuron. This cascade of ions hyperpolarises the neuron, thus increasing inhibitory effects and makes the neuron less excitable. Ethanol alters the enzyme kinetics enabling the ion...
The occurrence of action potential is a very short process. When action potential occurs in the neuron the sodium channels open along the axon and sodium comes in. Because the sodium is positive it make the inside of the axon positive. When both the inside and outside are comparative in charge the sodium storms rushing in and starts the depolarization of the action potential. After this happens the sodium channels begin to close and the potassium channels begin to ...
U.S. National Library of Medicine, 26 Sept. 2011. Web. The Web. The Web. 19 Nov. 2013.
The mechanism of action for Amphotericn B is that it binds with ergosterol to form a transmembrane that turns to monovalent ion leakage...
The current efficiency is an important parameter that determines the optimum range of applicability of electrodialysis. It is a measure of how effective ions are transported across the ion exchange membranes for a given applied current. It is calculated using the following equation [20, 21]:
7- When describing the properties of JNJ 40279486, the authors highlight the selectivity of the compound over the hERG channel. Explain wh...
Ed. David Zieve. U.S. National Library of Medicine, 26 Feb. 2014. Web. The Web.
Electrophysiology is the study of electrical properties of tissues and cells. It is said to be the “gold standard”, when investigating neuronal signalling (Massimo Scanziani et Michael Häusser, 2009). Measurements are taken of the voltage change or the electrical current on an extensive variety of scales from a single ion channel protein (e.g. potassium channels) to large organs (e.g. the heart). There are many areas in which electrophysiology can be applied to.