Ion Channel Reconstitution


Book Description

It is now over 30 years since the idea of ion-conducting pores burst on the elec trophysiological scene, 15 years since these were generalIy realized to be mem brane-spanning proteins, and 10 years since the first observations of single ion channels from higher organisms were made. During the past 5 years, several integral membrane channel proteins have been purified in a functionalIy competent state: the nicotinic acetylcholine receptor, the Na + channel, mitochondrial "VDAC," and a variety of porins. The stage is thus set to attack ion channels in the same ways that biochemists have been attacking enzymes for decades: isolation folIowed by functional analysis in as simple a system as possible, with a view towards understanding the molecular mechanisms ofthe protein's behavior and how this is related to the underlying molecular structure. This is always a daunting task, alI the more so with ion channels because of our still primitive and scanty understanding of channel structures and because of the difficulty in iso lating functionally active channel proteins. In this volume, which can be considered a biochemically slanted companion to Sakmann and Neher's Single-Channel Recording, I have tried to present a view of the current landscape of ion-channel reconstitution. These chapters illustrate not only the different approaches and techniques of the major practitioners of ion channel reconstitution but, as importantly, the varied motivations for doing this kind of work.




Ion Channels: Channel Biochemistry, Reconstitution, and Function


Book Description

Ion Channels Part A, Volume 651 in the Methods in Enzymology series, highlights new advances in the field with this new volume presenting interesting chapters on a variety of new developments on the topic. Each chapter is written by an international board of authors. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Methods in Enzymology series




Ion Channel Reconstitution Platform Allowing Simultaneous Recording from Multiple Bilayer Sites


Book Description

ABSTRACT The purpose of this study is to demonstrate that stable lipid bilayers can be set up on an array of silicon micropores and can be used as sites for self-inserting ion-channel proteins which can be studied independently of each other. In course of this study an acrylic based holder was designed and machined to ensure leak-free fluidic access to the silicon micropores and physical isolation of the individual array channels. To measure the ion-channel currents, we simulated, designed and manufactured low-noise transimpedance amplifiers and support circuits based on published patch clamp amplifier designs, using currently available surface-mount components. This was done in order to achieve a reduction in size and costs as well as isolation of individual channels without the need for multiplexing of the input. During the experiments performed, stable bilayers were formed across an array of four vertically mounted 30 m silicon micropores and OmpF porins were added for self insertion in each of the bilayers. To further demonstrate the independence of these bilayer recording sites, the antibiotic Ampicillin (2.5 mM) was added to one of the fluidic wells. The ionic current in each of the wells was recorded simultaneously. Sub-conductance states of Ompf porin were observed in two of the measurement sites. In addition, the conductance steps in the site containing the antibiotic could be clearly seen to be larger compared to those of the unmodified site. This is due to the transient blocking of ion flow through the porin due to translocation of the antibiotic. Based on this demonstration, ion-channel array reconstitution is a potential method for efficient electrophysiological characterization of different types of ion-channels simultaneously as well as for studying membrane permeation processes.




Ion Channels


Book Description

Modern applications of electrophysiologica techniques; Expression of ion channels; Expression of ion channels in Xenopus oocytes; Expression of ion channels using other systems; Reconstruction of ion channels in lipid bilayers; Recording of ion channels of cellular organelles and miroorganisms; Data storage and analysis.




Reconstitution of Mammalian Ion Channels in Droplet Bilayers


Book Description

Ion channel studies are important for scientific characterization of cellular processes and for the purpose of drug discovery. The sessile droplet bilayer platform allows for simple, fast, inexpensive and high-yield formation of artificial lipid bilayers and reconstitution of ion channels. We validated this bilayer formation platform with mammalian ion channels like Chloride Intracellular Channel 1 (CLIC1) and Voltage-gated potassium channel 1.2 (Kv1.2). Ion channel synthesis using traditional bacterial expression systems is a complex and time consuming process and it limits the number of eukaryotic proteins that can be expressed therein. We explored the use of in vitro protein synthesis and plasma membrane fractionation of commercially available mammalian cells for expressing and reconstituting ion channel proteins in planar lipid bilayers.




Ionic Channels in Cells and Model Systems


Book Description

This book is based on a series of lectures for a course on ionic channels held in Santiago, Chile, on November 17-20, 1984. It is intended as a tutorial guide on the properties, function, modulation, and reconstitution of ionic channels, and it should be accessible to graduate students taking their first steps in this field. In the presentation there has been a deliberate emphasis on the spe cific methodologies used toward the understanding of the workings and function of channels. Thus, in the first section, we learn to "read" single channel records: how to interpret them in the theoretical frame of kinetic models, which information can be extracted from gating currents in re lation to the closing and opening processes, and how ion transport through an open channel can be explained in terms of fluctuating energy barriers. The importance of assessing unequivocally the origin and purity of mem brane preparations and the use of membrane vesicles and optical tech niques in the stUGY of ionic channels are also discussed in this section. The patch-clamp technique has made it possible to study ion channels in a variety of different cells and tissues not amenable to more conven tional electrophysiological methods. The second section, therefore, deals with the use of this technique in the characterization of ionic channels in different types of cells, ranging from plant protoplasts to photoreceptors.




Planar Lipid Bilayers (BLM's) and Their Applications


Book Description

The lipid bilayer is the most basic structural element of cell membranes. A wide range of topics are covered in this volume, from the origin of the lipid bilayer concept, to current applications and experimental techniques. Each chapter in this volume is self-contained and describes a group's research, providing detailed methodology and key references useful for researchers. Lipid bilayer research is of great interest to many because of it's interdisciplinary nature. · Provides an overview of decades of research on the lipid bilayer· 38 contributed chapters, by leading scientists, cover a wide range of topics in one authoritative volume· Book coincides with 40th anniversary of BLM




Ion Channels: Channel Production and Optical Methods


Book Description

Ion Channels Part B, Volume 652 in the Methods in Enzymology series, highlights new advances in the field, with this new volume presenting interesting chapters on a variety of topics, including NMDAR, Pannexin, and CALHM, Making NaV1.4 and NaV1.7, TRPVs, Purification native nAChRs, GABAR Radu Aricescu, TRPV5/2, NaV1.5, KATP, TRPA1, TREK-1, SARS-CoV-2 3a ion channel, Ion channel conformational dynamics by encoded unnatural amino acid, Fluorescence lifetime measurement of absolute membrane potential, Fluorescent Toxins as Activity Sensors, FRET Analyses of Ion Channel Protein-Protein Interactions, Control of Ion Channel Gating with Photo-Switchable Tweezers, and Counting Subunits in Kv Channel Complexes. Provides the authority and expertise of leading contributors from an international board of authors Presents the latest release in the Methods in Enzymology series




Essential Ion Channel Methods


Book Description

The rapid growth of interest and research activity in ion channels is indicative of their fundamental importance in the maintenance of the living state. This volume was prepared with a view toward providing a sampling of the range of molecular and physical methods that are significant for the study of ion channels. As part of the Reliable Lab Solutions series, Essential Ion Channel Methods brings together chapters from volumes 293 and 294 of Methods in Enzymology. The chapters have been selected by the editor and updated, when possible, by their original authors to include new research and references. The result is a set of chapters which make use of graphics, comparisons to other methods, and provide tricks and approaches that make it possible to adapt methods to other systems. Methods are presented in a fashion that allows their replication by individuals new to the field, yet providing valuable information for seasoned investigators. Highlights top downloaded and cited chapters, authored by pioneers in the field and enhanced with graphics and easy to follow methods Loaded with detailed protocols developed and used by leaders in the field Refines, organizes and updates popular methods from one of our top selling series, Methods in Enzymology




Piezo Channels


Book Description

Piezo Channels, Volume 79, the latest volume in the Current Topics in Membranes series provides the necessary membrane research to assist readers in discovering the current state of a particular field and future directions. New chapters in the updated volume include A Tour de Force: The Discovery, Properties, and Function of Piezo Channels, Piezo1 Channels in Vascular Development and the Sensing of Shear Stress, the Origin of the Force: The Force-From-Lipids Principle Applied to Piezo Channels, Genetic Diseases of PIEZO1 and PIEZO2 Dysfunction, and The Structural Basis for Sensing by the Piezo1 Protein. Users of this series will find an up-to-date presentation of the current knowledge in the field of Piezo Channels. Written by leading experts in the field Contains original material, both textual and illustrative, that make it a very relevant reference Presented in a very comprehensive manner Ideal reference for both researchers in the field and general readers who will find this book to be relevant and up-to-date