A Brief History of Calcium Channel Discovery

Richard W. Tsien and Curtis F. Barrett The Key Role of Ca2+ Channels in Cellular Signaling

The stretch reflex represents the best-known and longest studied neural circuit. Unlike sensory circuits, for example in the visual system, the stretch reflex connects an external input to a behavioral output, both mechanical in nature, and is thus easily demonstrable without technical equipment....

Acquired Alterations in Transporter Expression and Function in Cholestasis

Exposure to cholestatic injury (e.g., drugs, hormones, proinflammatory cytokines, biliary obstruction/destruction), hereditary mutations of transporter genes, or the combination of both result in decreased expression and function of hepatobiliary transport systems. These molecular changes may ...

Actin and Myosin VIII in Plant Cell-Cell Channels

Jozef Samaj, Nigel Chaffey, Uday Tirlapur, Jan Jasik, Andrej Hlavacka, Zhan Feng Cui, Dieter Volkmann, Diedrik Menzel and Frantisek Baluska

Plasmodesmata (PD) are cell-cell channels interconnecting all the cells of the plant body into a huge syncytium, which makes plants ‘supracellular’ organisms. Recent studies have clearly revealed that both the targeting and gating of PD is highly regulated. Importantly, it is known that molecules be...

Bile Acid-Mediated Apoptosis in Cholestasis

H injury by inducing apoptosis. Toxic bile acids induce apoptosis by activating cell surface membrane death receptors. The activated death receptors stimulate a signaling cascade involving the pro-apoptotic Bcl-2 poteins Bid and Bax. The proapoptotic Bcl-2 proteins initiate mitochondrial injury, ...

Biochemical Studies of Voltage- Gated Ca2+ Channels

William A. Catterall

Voltage-gated Ca2+ channels mediate Ca2+ entry into cells in response to membrane depolarization. Electrophysiological studies reveal different Ca2+ currents designated L-, N-, P-, Q-, R-, and T-type. The high-voltage-activated Ca2+ channels that have been characterized biochemically are complexe...

Block of Voltage-Gated Calcium Channels by Peptide Toxins

Christina I. Schroeder, Richard J. Lewis and David J. Adams

Structurally, the calcium channels are closely related to sodium channels, with the main structurally significant difference being the positioning and nature of the residues that line the selectivity filter in the pore of the channel. There are at least six pharmacologically distinct calcium chan...

Bone Disease in Chronic Cholestatic Liver Disease

Harold Dobnig and Astrid Fehrleiter

Patients with chronic cholestatic liver disease are especially prone to osteoporosis. Hepatic osteodystrophy typically presents as low turnover osteoporosis with initially normal bone resorption that becomes elevated as disease progresses. The mechanisms leading to low bone formation remain largely...

Ca2+ Chemistry Storage and Transport in Biologic Systems: An Overview

Tashi G. Kinjo and Paul P.M. Schnetkamp

Calcium ions play a critical role in most if not all cellular processes. It has even been demonstrated that Ca2+ currents in root tips, in combination with gravity, are re sponsible for their downward growth.1 Most of these effects are mediated by both temporally and spatially tightly controlle...

Ca2+-Dependent Modulation of Voltage-Gated Ca2+ Channels

Amy Lee and William A. Catterall

Abstract The passage of Ca2+ ions through voltage-gated Ca2+ channels triggers a wide range of signaling pathways but also fundamentally regulates further Ca2+ influx through these channels. Cav1.2 (L-type) and Cav2.1 (P/Q-type) channels undergo a dual feedback regulation by Ca2+, which is manif...

Calcium Channel Block and Inactivation: Insights from Structure-Activity Studies

Steffen Hering, Stanislav Sokolov, Stanislav Berjukow, Rainer Marksteiner, Eva Margreiter and Evgeni N. Timin

During an action potential calcium (Ca2+) ions enter the cell through voltage-gated Ca2+ channels (Cav). Cav channels first open and subsequently close before recovering to the resting state (Fig. 1A). The process of channel closure during maintained membrane depolarization is called “inactivatio...

Calcium Channelopathies

Nancy M. Lorenzon and Kurt G. Beam

Many cellular functions are directly or indirectly regulated by the free cytosolic calcium concentration. Thus, calcium levels must be very tightly regulated in time, space and amount. Intracellular calcium ions are essential second messengers and play a role in many functions including, action p...

Calcium Channels as Therapeutic Targets

Francesco Belardetti and Sian Spacey

Voltage-dependent calcium channels link membrane potential changes of excitable cells to important intracellular processes, including regulated secretion of neurotransmitters and hormones, muscle contraction and gene transcription (see Chapters 1,8,20-22). This critical role makes them attractive...

Calcium Channels in the Heart

Stéphanie Barrère-Lemaire, Matteo E. Mangoni and Joël Nargeot

In the sixties, the first Ca2+ currents were recorded by voltage-clamp techniques on multi-cellular cardiac strips 1-4 It is only since 1980 that the development of enzymatic dissociation methods allowed the first electrophysiological recordings on isolated cardiac cells.3 The whole cell patch...

Cell-Cell Channels and Their Implications for Cell Theory

Frantisek Baluska*, Dieter Volkmann and Peter W. Barlow

Cells show diverse appearances and sizes, ranging from some 30 nanometers up to several meters in length. Besides the classical prokaryotic and eukaryotic cells, there are also very bizarre cells such as the highly reduced symbiotic mitosomes which lack DNA. Other examples of extremely small cells i...

Cell-Cell Communication in Wood

J.R. Barnett

The sapwood of trees contains living cells in the form of ray and axial parenchyma. Communication between these cells is important in controlling the differentiation of xylem cells, movement of nutrients and water, defence against pathogens and damage repair. These parenchyma cells are therefore lin...

Cell-Cell Fusion: Transient Channels Leading to Plasma Membrane Merger

William A. Mohler

Despite the diversity of intercellular connections that are the subject of this book, most eukaryotic cells retain their distinct character as mononucleated compartments. Their membranes describe morphologically separate cytoplasms, while electrical connectivity and low-flux intercellular exchan...

Cell-Cell Movements of Transcription Factors in Plants

Alexis Maizel

In the last few years, the intercellular trafficking of regulatory proteins has emerged as a novel mechanism of cell-to-cell communication in plant development. Here I present a review of the documented cases of transcription factors movement in plants and examine the common themes underlying these ...

Cell-Cell Transport of Homeoproteins: With or Without Channels?

Alain Joliot and Alain Prochiantz

Homeoproteins are a class of transcription factors that have the unusual property of intercellular transfer, both in metaphytes and in metazoans. Here we discuss the cellular mechanisms and the function of this transfer.

Cellular and Tissue Expression of Rat DMT1 / Nramp 2

Evan H. Morgan

Evidence that rat DMT1 functions as a membrane transporter of iron was established by expression cloning in Xenopus laevis oocytes and by investigations in the Belgrade rat in which iron metabolism is impaired due to a missence mutation of the protein. DMT1 can transport several divalent metal...

Channels across Endothelial Cells

Radu V. Stan

The evolution of multicellular organisms entailed the formation of biological compartments separated by epithelial cellular barriers. As a consequence, strategies have evolved to move/ exchange materials between these compartments for nutrition, wastes removal and information exchange, while st...

Cholestasis: An Intracellular "Traffic Jam"

Mutations in the coding region of BSEP which result in its absence from the bile canalicular membrane are manifested by progressive cholestasis and liver damage. We have proposed that defects in intracellular trafficking and/or posttranslational regulation of BSEP may produce a similar pheno...

Cytonemes As Cell-Cell Channels in Human Blood Cells

Svetlana Ivanovna Galkina, Anatoly Georgievich Bogdanov, Georgy Natanovich Davidovich and Galina Fedorovna Sud’ina

Human blood cell similar to embryonic and nerve cells can extend thin and very long exten- sions having the same diameter along the entire length called cytonemes. Cytonemes were shown to connect blood cells over a distance of several cell diameters and transport membrane proteins, lipids and i...

Cytoplasmic Bridges as Cell-Cell Channels of Germ Cells

Sami Ventelä

Transient intercellular bridges are seen between a wide variety of cells before the completion of cytokinesis.1 However, these are distinct from stable intercellular bridges that remain persistent after incomplete cytokinesis.2 The diameter of the cytoplasmic bridges is rather big, 1-10 mm, compared...

Cytoplasmic Bridges in Volvox and Its Relatives

Harold J. Hoops, Ichiro Nishii and David L. Kirk

The volvocaceans are a closely related group of green flagellates that range in size and complexity from colonial forms that contain a small number of identical cells, to Volvox in which there is a division of labor between several thousand terminally differentiated somatic cells and a small number ...

Determinants of G Protein Inhibition of Presynaptic Calcium Channels

Aparna Nirdosh and Gerald W. Zamponi

The modulation of presynaptic calcium channels following the activation of G-protein coupled receptors is a key regulatory mechanism of synaptic transmission. The past two decades have yielded a tremendous advance in our understanding of this phenomenon at the molecular level. It is now widely ac...