Ion channels: Gate expectations

  title={Ion channels: Gate expectations},
  author={Maria L. Garcia},
The opening and closing — gating — of ion channels in response to specific stimuli is crucial for cell function. The membrane-partitioning activities of two venom toxins give insights into the mechanisms involved. 
The gramicidin ion channel: a model membrane protein.
Special emphasis is given to the role and orientation of tryptophan residues in channel structure and function and recent spectroscopic approaches that have highlighted the organization and dynamics of the channel in membrane and membrane-mimetic media. Expand
Direct Evidence That Receptor Site-4 of Sodium Channel Gating Modifiers Is Not Dipped in the Phospholipid Bilayer of Neuronal Membranes*
It is shown that in general, scorpion β-toxins do not partition in neuronal membranes and that in the case in which a depressantβ-toxin partitions in insect neuronal membranes, this partitioning is unrelated to its interaction with the receptor site and the effect on the gating properties of the sodium channel. Expand
Ion channels and D-amino acids
It is interesting to note that gramicidin represents a useful model for realistic determination of conformational preference of proteins in a membrane environment, in spite of the alternating sequence of L-D chirality generally not encountered in naturally occurring peptides and proteins. Expand
Is lipid bilayer binding a common property of inhibitor cysteine knot ion-channel blockers?
It is shown that various ICK peptides demonstrate markedly different modes of interaction with large unilamellar lipid vesicles, showing that bilayer partitioning is not a universal property of the ICk peptides interacting with ion channels. Expand
Mechanosensitive Channels in Striated Muscle and the Cardiovascular System: Not Quite a Stretch Anymore
The role of transient receptor potential channels, several of which have been implicated as mechanosensitive channels, in the pathogenesis of adverse cardiac remodeling and as potential therapeutic targets in the treatment of heart failure are focused on. Expand
Screening ion-channel ligand interactions with passive pumping in a microfluidic bilayer lipid membrane chip.
Dose-dependent transient blocking of α-hemolysin with β-cyclodextrin and polyethylene glycol is demonstrated and dose-dependent blocking studies of the KcsA potassium channel with tetraethylammonium show the potential for determining IC50 values. Expand
Dual modulation of CNS voltage-gated calcium channels by cannabinoids: Focus on CB1 receptor-independent effects.
Recent studies on the modulation of different types of VGCCs by cannabinoids are summarized, the evidence for and implications of the CB1R-independent modulation are highlighted, and the concept, that direct interaction of cannabinoids andVGCCs is as important in regulation of VG CCs function as the CB 1R-mediated effects are put forward. Expand
1.2 Å X-ray Structure of the Renal Potassium Channel Kv1.3 T1 Domain
Here we present the structure of the T1 domain derived from the voltage-dependent potassium channel Kv1.3 of Homo sapiens sapiens at 1.2 Å resolution crystallized under near-physiological conditions.Expand
Effect of graded hydration on the dynamics of an ion channel peptide: a fluorescence approach.
The results show that tryptophans in gramicidin, present in the single-stranded beta6.3 conformation, experience slow solvent relaxation giving rise to red-edge excitation shift (REES), and it is concluded that REES could prove to be a potentially sensitive tool to explore the dynamics of proteins under conditions of changing hydration. Expand
Receptor-independent actions of cannabinoids on cell membranes: focus on endocannabinoids.
  • M. Oz
  • Chemistry, Medicine
  • Pharmacology & therapeutics
  • 2006
Findings indicate that additional molecular targets for endocannabinoids exist and that these targets may represent novel sites for cannabinoids to alter either the excitability of the neurons or the response of the neuronal systems. Expand


A membrane-access mechanism of ion channel inhibition by voltage sensor toxins from spider venom
VSTX1, small hydrophobic poisons and anaesthetic molecules reveal a common theme of voltage sensor inhibition through lipid membrane access, consistent with the recent proposal that the sensor in voltage-dependent K+ channels is located at the membrane–protein interface. Expand
The principle of gating charge movement in a voltage-dependent K+ channel
It is concluded that the voltage-sensor paddles operate somewhat like hydrophobic cations attached to levers, enabling the membrane electric field to open and close the pore. Expand
Functional analysis of an archaebacterial voltage-dependent K+ channel
The functional characterization of a voltage-dependent K+ (KV) channel from a hyperthermophilic archaebacterium from an oceanic thermal vent is presented and it is shown that this channel possesses all the functional attributes of classical neuronal KV channels. Expand
Stirring up controversy with a voltage sensor paddle
Three disparate models of the way voltage-gated ion channels sense and respond to changes in membrane potential are compared and critically discussed. Expand
X-ray structure of a voltage-dependent K+ channel
The structure of KvAP, a voltage-dependent K+ channel from Aeropyrum pernix, is presented and a crystal structure of the full-length channel at a resolution of 3.2 Å is determined, which suggests that the voltage-sensor paddles move in response to membrane voltage changes, carrying their positive charge across the membrane. Expand
Interaction between Extracellular Hanatoxin and the Resting Conformation of the Voltage-Sensor Paddle in Kv Channels
The interaction of externally applied Hanatoxin with the voltage-sensor paddle in Kv channels is studied and it is shown that the toxin binds tightly even at negative voltages where the paddle is resting and the channel is closed. Expand
A Hot Spot for the Interaction of Gating Modifier Toxins with Voltage-Dependent Ion Channels
It is suggested that the COOH-terminal end of S3 within repeat IV contributes to forming a receptor for ω-Aga-IVA, a gating modifier toxin from spider venom that inhibits voltage-gated Ca2+ channels by shifting activation to more depolarized voltages. Expand
Bilayer-dependent inhibition of mechanosensitive channels by neuroactive peptide enantiomers
The results suggest that modulation of membrane proteins by amphipathic peptides—mechanopharmacology—involves not only the protein itself but also the surrounding lipids, and the surprising efficacy of the d form of GsMTx4 has important therapeutic implications, because d peptides are not hydrolysed by endogenous proteases and may be administered orally. Expand
Molecular Surface of Tarantula Toxins Interacting with Voltage Sensors in Kv Channels
The active surface of SGTx contains a ring-like assembly of highly polar residues, with two basic residues that are particularly critical, concentrated around a hydrophobic protrusion containing critical aliphatic and aromatic residues. Expand
Ion Channels And Disease