Are Apical Membrane Ion Channels Involved in Frog Taste Transduction?.

1987 ◽  
Vol 510 (1 Olfaction and) ◽  
pp. 362-365 ◽  
Author(s):  
M. SCOTT HERNESS
Keyword(s):  
Ion Channels ◽  
Apical Membrane ◽  
Taste Transduction

scholarly journals Molecular mechanisms of taste transduction

2002 ◽  
Vol 74 (7) ◽  
pp. 1125-1133 ◽  
Author(s):  
Robert F. Margolskee
Keyword(s):  
Ion Channels ◽  
Molecular Cloning ◽  
G Proteins ◽  
Molecular Mechanisms ◽  
Transmembrane Helix ◽  
Taste Receptor ◽  
Sweet Taste ◽  
Chemical Diversity ◽  
Chemical Information ◽  
Taste Transduction

Taste transduction is a specialized form of signal transduction by which taste receptor cells (TRCs) encode at the cellular level information about chemical substances encountered in the oral environment (so-called tastants). Bitter and sweet taste transduction pathways convert chemical information into a cellular second messenger code utilizing cyclic nucleotides, inositol trisphosphate, and/or diacyl glycerol. These messengers are components of signaling cascades that lead to TRC depolarization and Ca++ release. Bitter and sweet taste transduction pathways typically utilize taste-specific or taste-selective seven transmembrane-helix receptors, G proteins, effector enzymes, second messengers, and ion channels. The structural and chemical diversity of tastants has led to the need for multiple transduction mechanisms. Through molecular cloning and data mining, many of the receptors, G proteins, and effector enzymes involved in transducing responses to bitter and sweet compounds are now known. New insights into taste transduction and taste coding underlying sweet and bitter taste qualities have been gained from molecular cloning of the transduction elements, biochemical elucidation of the transduction pathways, electrophysiological analysis of the function of taste cell ion channels, and behavioral analysis of transgenic and knockout models.

scholarly journals Cell biology and physiology of the uroepithelium

2009 ◽  
Vol 297 (6) ◽  
pp. F1477-F1501 ◽  
Author(s):  
Puneet Khandelwal ◽  
Soman N. Abraham ◽  
Gerard Apodaca
Keyword(s):  
Ion Channels ◽  
High Resistance ◽  
Barrier Function ◽  
Cell Biology ◽  
Apical Membrane ◽  
Cell Layer ◽  
Water Flux ◽  
The Other ◽  
Uropathogenic Bacteria ◽  
Urinary Space

The uroepithelium sits at the interface between the urinary space and underlying tissues, where it forms a high-resistance barrier to ion, solute, and water flux, as well as pathogens. However, the uroepithelium is not simply a passive barrier; it can modulate the composition of the urine, and it functions as an integral part of a sensory web in which it receives, amplifies, and transmits information about its external milieu to the underlying nervous and muscular systems. This review examines our understanding of uroepithelial regeneration and how specializations of the outermost umbrella cell layer, including tight junctions, surface uroplakins, and dynamic apical membrane exocytosis/endocytosis, contribute to barrier function and how they are co-opted by uropathogenic bacteria to infect the uroepithelium. Furthermore, we discuss the presence and possible functions of aquaporins, urea transporters, and multiple ion channels in the uroepithelium. Finally, we describe potential mechanisms by which the uroepithelium can transmit information about the urinary space to the other tissues in the bladder proper.

Ion Channels and Taste Transduction

2021 ◽  
pp. 137-149
Author(s):  
Stephen D. Roper
Keyword(s):  
Ion Channels ◽  
Taste Transduction

Staphylococcus aureus alpha-toxin permeabilizes the basolateral membrane of a Cl(-)-secreting epithelium

1992 ◽  
Vol 263 (1) ◽  
pp. L104-L112 ◽  
Author(s):  
L. S. Ostedgaard ◽  
D. M. Shasby ◽  
M. J. Welsh
Keyword(s):  
Staphylococcus Aureus ◽  
Ion Channels ◽  
Prolonged Exposure ◽  
Apical Membrane ◽  
Basolateral Membrane ◽  
Transport Processes ◽  
Epithelial Cell Line ◽  
Alpha Toxin ◽  
Cl Secretion ◽  
Cl Channels

Apical membrane ion channels control the rate of transepithelial electrolyte transport in many epithelia. One way to study such channels in their native location, the apical membrane, is to eliminate the resistance of the basolateral membrane to ion flow. Then the opening and closing of apical channels can be measured as a transepithelial current, free from the influence of basolateral membrane transport processes. To develop a method that would permeabilize an epithelial basolateral membrane to ions and nucleotides, we examined the effect of Staphylococcus aureus alpha-toxin on the Cl(-)-secreting T84 epithelial cell line. alpha-Toxin permeabilized the basolateral, but not the apical membrane to Cl-, adenosine 3',5'-cyclic monophosphate (cAMP), and GTP. However, the integrity of signal-transduction pathways, the regulation of apical membrane Cl- channels, and the transepithelial resistance remained intact. In the course of examining the effect of ATP, we found that the basolateral membrane contained purinergic receptors that both stimulated Cl- secretion on their own and, at high concentrations, inhibited cAMP-induced Cl- secretion. These effects of extracellular ATP were eliminated after prolonged exposure to ATP, suggesting receptor downregulation. In addition, depletion of intracellular ATP following permeabilization prevented cAMP-dependent regulation of apical Cl- channels. We conclude that alpha-toxin may prove to be a useful tool for studying the regulation and properties of apical membrane ion channels.

What Is New About the Structure of the Epithelial Na+ Channel ?

Physiology ◽  
1996 ◽  
Vol 11 (5) ◽  
pp. 195-201
Author(s):  
CM Canessa
Keyword(s):  
Ion Channels ◽  
Apical Membrane ◽  
Na Channel ◽  
Full Activity ◽  
New Family ◽  
Epithelial Na Channel ◽  
Tight Epithelium

The epithelial Na+ channel (ENaC) in the apical membrane of tight epithelium represents the first member of a new family of ion channels. The channel is formed by the association of three homologous subunits, a-, b-, and g-ENaC, that functionally complement to give full activity to the channel complex.

Role of PKC isozymes in water transport in toad urinary bladder

1991 ◽  
Vol 49 ◽  
pp. 302-303
Author(s):  
A.J. Mia ◽  
L.X. Oakford ◽  
T. Yorio
Keyword(s):  
Urinary Bladder ◽  
Apical Membrane ◽  
Membrane Surface ◽  
Protein A ◽  
Cell Types ◽  
Leukemic Cells ◽  
Toad Urinary Bladder ◽  
Pkc Isozymes ◽  
Antibody Labeling

Protein kinase C (PKC) isozymes, when activated, are translocated to particulate membrane fractions for transport to the apical membrane surface in a variety of cell types. Evidence of PKC translocation was demonstrated in human megakaryoblastic leukemic cells, and in cardiac myocytes and fibroblasts, using FTTC immunofluorescent antibody labeling techniques. Recently, we reported immunogold localizations of PKC subtypes I and II in toad urinary bladder epithelia, following 60 min stimulation with Mezerein (MZ), a PKC activator, or antidiuretic hormone (ADH). Localization of isozyme subtypes I and n was carried out in separate grids using specific monoclonal antibodies with subsequent labeling with 20nm protein A-gold probes. Each PKC subtype was found to be distributed singularly and in discrete isolated patches in the cytosol as well as in the apical membrane domains. To determine if the PKC isozymes co-localized within the cell, a double immunogold labeling technique using single grids was utilized.

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