Potassium channels are ubiquitous, being present in all living organisms. These proteins share common structural elements, which confer common functional features. In general, all K+ channels have a high selectivity for K+, and are blocked by cations of similar dimensions, such as Cs+ and Ba2+. Mutations in the pore region tend to lead to either the total loss of function or K+ selectivity. We ...

Zn2+ can induce a conformational change of Band 3 with concomitant inhibition of its anion transport activity of human erythrocyte membrane vesicles only from the cytoplasmic side. The Zn2+ inhibition exhibits a dose-dependent manner with an apparent half maximal concentration of 50 microM ZnCl2 and can be reversed by 0.5 mM EDTA, but not by 1 mM dithiothreitol. The Zn2+ effect is specific and ...

The intracellular Ca2+ concentration of nearly all cells is kept at submicromolar levels. The magnitudes of transmembrane Ca2+ movement that maintain this steady state in the human red blood cell have long been debated. Although there is agreement that the physiologic extrusion of Ca2+ by the well-characterized Ca2+. ATPase amounts to 45 mumol/liter cells per h (1982. Nature (Lond.). 298:478-48...

The temporal resolution of carbon-fiber microelectrodes has been exploited to examine the plasticity of quantal secretory events at individual adrenal medullary cells. The size of individual quantal events, monitored by amperometric oxidation of released catecholamines, was found to be dependent on the extracellular ionic composition, the secretagogue, and the order of depolarization delivery. ...

Potassium channels show amazing discrimination, favoring K+ over other monovalent cations, such as Na+ and Li+. Although structural and functional studies have revealed much about the KcsA channel, including the residues physically involved in ion permeation and the conformational changes involved in channel opening, the basis for ion selectivity is still an open question. Now, MacKinnon and co...

A solution combustion route for the synthesis of Eu-activated M2V2O7 (M 0 Sr, Ba) and their luminescent properties have been investigated. Structure and luminescent characteristics of Sr2V2O7:Eu 3+ and Ba2V2O7:Eu 3+ nanophosphors have been studied by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, fluorescence spectrometry and Fourier transform infra-red spect...

The influence of both the structure and the conformation of polyuronates and the linear charge density of these macromolecules upon the interaction of some divalent cations with their carboxyl groups is discussed. Several presumed mechanisms of cation binding to polyuronates have been mentioned and evaluated from our cited experimental data: determination of activity coefficients of Ca2 and Sr2...

Mn4+-activated phosphors are emerging as a novel class of deep red/near-infrared emitting persistent luminescence materials for medical imaging as a promising alternative to Cr3+-doped nanomaterials. Currently, it remains a challenge to improve the afterglow and photoluminescence properties of these phosphors through a traditional high-temperature solid-state reaction method in air. Herein we p...