Patch Fluorometry: Shedding New Light on Ion Channels

Physiology ◽  
2006 ◽  
Vol 21 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Jie Zheng
Keyword(s):  
Ion Channels ◽  
Structure Function ◽  
Direct Observation ◽  
Single Channel ◽  
New Approach ◽  
Channel Protein ◽  
A Cell ◽  
Function Relationship ◽  
Free Membrane ◽  
Membrane Patch

Patch fluorometry has emerged as a new approach to the study of the structure-function relationship in membrane-embedded functional ion channels. Simultaneous fluorescent and electrical recordings are achieved from a small number of channels in a cell-free membrane patch, yielding high recording sensitivities. Further improvement of this approach should permit direct observation of the gating motion of a single-channel protein.

scholarly journals Structure–Function Relationship and Physiological Roles of Transient Receptor Potential Canonical (TRPC) 4 and 5 Channels

Cells ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 73
Author(s):  
Jinsung Kim ◽  
Juyeon Ko ◽  
Chansik Hong ◽  
Insuk So
Keyword(s):  
Ion Channels ◽  
Structure Function ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Trpc Channels ◽  
Transient Receptor Potential Canonical ◽  
Structure Function Relationship ◽  
Transient Receptor ◽  
Function Relationship ◽  
Relationship Of

The study of the structure–function relationship of ion channels has been one of the most challenging goals in contemporary physiology. Revelation of the three-dimensional (3D) structure of ion channels has facilitated our understanding of many of the submolecular mechanisms inside ion channels, such as selective permeability, voltage dependency, agonist binding, and inter-subunit multimerization. Identifying the structure–function relationship of the ion channels is clinically important as well since only such knowledge can imbue potential therapeutics with practical possibilities. In a sense, recent advances in the understanding of the structure–relationship of transient receptor potential canonical (TRPC) channels look promising since human TRPC channels are calcium-permeable, non-selective cation channels expressed in many tissues such as the gastrointestinal (GI) tract, kidney, heart, vasculature, and brain. TRPC channels are known to regulate GI contractility and motility, pulmonary hypertension, right ventricular hypertrophy, podocyte injury, seizure, fear, anxiety-like behavior, and many others. In this article, we tried to elaborate recent findings of Cryo-EM (cryogenic-electron microscopy) based structural information of TRPC 4 and 5 channels and domain-specific functions of the channel, such as G-protein mediated activation mechanism, extracellular modification of the channel, homo/hetero-tetramerization, and pharmacological gating mechanisms.

Ion Channels and Human Genetic Diseases

Physiology ◽  
1996 ◽  
Vol 11 (1) ◽  
pp. 36-42 ◽  
Author(s):  
CV Rojas
Keyword(s):  
Functional Analysis ◽  
Ion Channels ◽  
Structure Function ◽  
Genetic Diseases ◽  
Structure Function Relationship ◽  
Function Relationship ◽  
Relationship Of

Ion channels have lately received much attention by geneticists and molecular biologists owing to the discovery of several inherited human "ion channels disorders". Important contributions to the understanding not only of pathogenesis, but also of the structure-function relationship of ion channels, have come from the functional analysis of these natually occurring mutant channels.

scholarly journals Molecular Choreography and Structure of Ca2+ Release-Activated Ca2+ (CRAC) and KCa2+ Channels and Their Relevance in Disease with Special Focus on Cancer

Membranes ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 425
Author(s):  
Adéla Tiffner ◽  
Isabella Derler
Keyword(s):  
Signal Transduction ◽  
Ion Channels ◽  
Structure Function ◽  
Human Body ◽  
Current Knowledge ◽  
Special Focus ◽  
Action Mechanisms ◽  
Function Relationship ◽  
Relationship Of ◽  
Cellular Components

Ca2+ ions play a variety of roles in the human body as well as within a single cell. Cellular Ca2+ signal transduction processes are governed by Ca2+ sensing and Ca2+ transporting proteins. In this review, we discuss the Ca2+ and the Ca2+-sensing ion channels with particular focus on the structure-function relationship of the Ca2+ release-activated Ca2+ (CRAC) ion channel, the Ca2+-activated K+ (KCa2+) ion channels, and their modulation via other cellular components. Moreover, we highlight their roles in healthy signaling processes as well as in disease with a special focus on cancer. As KCa2+ channels are activated via elevations of intracellular Ca2+ levels, we summarize the current knowledge on the action mechanisms of the interplay of CRAC and KCa2+ ion channels and their role in cancer cell development.

scholarly journals Direct observation of structure-function relationship in a nucleic acid-processing enzyme

Science ◽  
2015 ◽  
Vol 348 (6232) ◽  
pp. 352-354 ◽  
Author(s):  
M. J. Comstock ◽  
K. D. Whitley ◽  
H. Jia ◽  
J. Sokoloski ◽  
T. M. Lohman ◽  
...  
Keyword(s):  
Nucleic Acid ◽  
Structure Function ◽  
Direct Observation ◽  
Processing Enzyme ◽  
Structure Function Relationship ◽  
Acid Processing ◽  
Function Relationship

Stochastic properties of ion channel openings and bursts in a membrane patch that contains two channels: evidence concerning the number of channels present when a record containing only single openings is observed

1990 ◽  
Vol 240 (1299) ◽  
pp. 453-477 ◽  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Rate Constants ◽  
Single Channel ◽  
Large Range ◽  
Active Channels ◽  
Exact Calculations ◽  
Stochastic Properties ◽  
Membrane Patch ◽  
Simultaneous Activity

If a single ion channel record is observed in which two ion channels are never simultaneously open, then it is often of interest to know whether the observations indeed arose from the activity of only one ion channel. This question can be answered if it is possible to calculate the distribution of the duration of runs of single openings in a membrane patch that contains two active channels. If the observed run of single openings is much longer than that expected for a patch with two channels it is likely that only one channel was active. An approximate method is presented for calculating the distribution of the duration of runs of single openings in a patch with two active channels; this method has the advantage that it can be calculated from observable quantities, and requires no knowledge of the details of the ion-channel mechanism or its rate constants. The accuracy of this approximation is tested by exact calculations of the properties of runs of single openings, and of single bursts, for two specific mechanisms and a large range of rate constants. The approximation is good in all cases in which openings occur singly, or in closely spaced bursts. If, as is common in practice, openings occur in clusters that are separated by long shut periods, then overlap of clusters from two different channels may be detected, if no double opening is produced, as a period in the middle of a cluster in which the probability of being open doubles. The results derived here can be applied to such a period to test whether it results from the simultaneous activity of two channels, rather than from a change in the properties of a single channel.

Membrane patches as ion channel probes for scanning ion conductance microscopy

2016 ◽  
Vol 193 ◽  
pp. 81-97 ◽  
Author(s):  
Wenqing Shi ◽  
Yuhan Zeng ◽  
Lushan Zhou ◽  
Yucheng Xiao ◽  
Theodore R. Cummins ◽  
...  
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Single Channel ◽  
Donor Cell ◽  
Bk Channels ◽  
Ion Conductance ◽  
Current Time ◽  
Scanning Ion Conductance Microscopy ◽  
Close Proximity ◽  
Membrane Patch

We describe dual-barrel ion channel probes (ICPs), which consist of an open barrel and a barrel with a membrane patch directly excised from a donor cell. When incorporated with scanning ion conductance microscopy (SICM), the open barrel (SICM barrel) serves to measure the distance-dependent ion current for non-invasive imaging and positioning of the probe in the same fashion of traditional SICM. The second barrel with the membrane patch supports ion channels of interest and was used to investigate ion channel activities. To demonstrate robust probe control with the dual-barrel ICP-SICM probe and verify that the two barrels are independently addressable, current–distance characteristics (approach curves) were obtained with the SICM barrel and simultaneous, current–time (I–T) traces were recorded with the ICP barrel. To study the influence that the distance between ligand-gated ion channels (i.e., large conductance Ca2+-activated K+ channels/BK channels) and the ligand source (i.e., Ca2+ source) has on channel activations, ion channel activities were recorded at two fixed probe–substrate distances (Dps) with the ICP barrel. The two fixed positions were determined from approach curves acquired with the SICM barrel. One position was defined as the “In-control” position, where the probe was in close proximity to the ligand source; the second position was defined as the “Far” position, where the probe was retracted far away from the ligand source. Our results confirm that channel activities increased dramatically with respect to both open channel probability and single channel current when the probe was near the ligand source, as opposed to when the probe was far away from the ligand source.

Sign in / Sign up

Export Citation Format

Share Document