From Ion Channels to Cell-to-Cell Conversations

Ion channels allow us to see nature in all its magnificence, to hear a Bach suite, to smell the aroma of grandmother's cooking, and, in this regard, they put us in contact with the external world. These ion channels are protein molecules located in the cell membrane. In complex organisms, cells need to communicate in order to know about their metabolic status and to act in a coordinate manner. The latter is also accomplished by a class of ion channels able to pierce the lipid bilayer membranes of two adjacent cells. These intercellular channels are the functional subunits of gap junctions. Accordingly, the book is divided in two parts: the first part is dedicated to ion channels that look to the external world, and the second part is dedicated to gap junctions found at cell interfaces. This book is based on a series of symposia for a meeting on ion channels and gap junctions held in Santiago, Chile, on November 28-30, 1995. The book should be useful to graduate students taking the first steps in this field as well as a reference for the aficionado. The aim of the meeting was mainly to show the impact of various modern techniques, including cell biology, molecular biology, biophysics, and molecular genetics techniques in the study of these ubiquitous intrinsic membrane proteins. Molecular-genetics techniques paved the road to the manipulation of the channel forming molecules.

Texte du rabat

This book investigates molecular events that occur in different channels and specialized membrane domains during cell interactions with the external world as well as between cells of the same or different organs. The text addresses the impact of cell and molecular biology, biophysics, and molecular genetics techniques in the study of ion channels. Contributions discuss such topics as the molecular origin of voltage dependence in ion channels, different aspects of calcium-activated K+ channels of large conductance, progress in gap junction tunnels, and the process of exocytosis.

Contenu
I. Ion Channels in Contact with the External World.- 1 The Molecular Origin of Voltage Dependence in Ionic Channels.- 2 Inward Rectification by an Activation Gating Mechanism.- 3 Assembly of Shaker K-Channels from a Random Mixture of Subunits Carrying Different Mutations.- 4 New Insights into the Topography, Gating and Modulation of MaxiK Channels.- 5 Shifts of Macroscopic Current Activation in Partially Blocked Sodium Channels. Interaction between the Voltage Sensor and a ?-Conotoxin.- 6 ? Subunit Modulation of the Coupling between Charge Movement and Pore Opening in Calcium Channels.- 7 Thermodynamic Double Mutant Cycles with the Shaker K+ Channel and a Peptide Inhibitor Define the Spatial Location of Pore-Forming Residues.- 8 Barium as a Probe of the Molecular Architecture of the Pore of K+ Channels.- 9 Possible Participation of a cAMP Regulated K+ Channel from the Sea Urchin Sperm in the Speract Response.- 10 Gating and Selectivity Properties of a cAMP-Activated K+Selective Channel from Drosophila Larval Muscle.- 11 Regulation of Ca2+ and Na Channels in GH3 Cells by Epidermal Growth Factor.- 12 Physical State of the Nicotinic Acetylcholine Receptor Membrane and Modulation of the Receptor Channel by the Lipid Environment.- 13 Amiloride-Sensitive Na+ Channels and Human Hypertension.- 14 Anion Channels Involved in Volume Regulation: A Common Pathway for Chloride and Organic Osmolyte Permeation?.- 15 Volume-Regulated Anion Channels and Cytoskeletal Interaction.- 16 Inhibitory Responses to Odorants in Vertebrate Olfactory Neurons.- 17 Multiple Pathways in Invertebrate Visual Transduction.- II. Intercellular Channels.- 18 Structure and Function of Cell-to-Cell Channels Purified from the Lens and Hemichannels Expressed in Oocytes.- 19 Studies of Voltage Gating GapJunctions and Hemichannels Formed by Connexin Proteins.- 20 Gap Junctions between Leukocyte and Endothelium: Expression of Connexin 43 in Adherent or Activated Cells.- 21 Regulation of Gap Junctions in Rat Liver during Acute and Chronic CCl4-Induced Liver Injury.- 22 Cardiac Myocytes Gap Junctions: Phosphorylation of CX43 through a Protein Kinase C-Dependent Pathway.- 23 Regulation of Lens Gap Junctions.- 24 Molecular Physiology of Gap Junction Channels Formed by Connexin43.- 25 A Possible Physiological Role of the Major Intrinsic Protein of the Ocular Lens.- 26 Regulation of Smooth Muscle Activity and Gap Junctions by Sexual Hormones in the Rat Oviduct.- 27 Intercellular Calcium Signaling in Liver.- 28 Current Electrophysiological Techniques to Study Exocytosis.