The Ca2+ release-activated Ca2+ (CRAC) channel is the most well-documented of the store-operated ion channels that are widely expressed and are involved in many important biological processes. However, the regulation of the CRAC channel by intracellular or extracellular messengers as well as its molecular identity is largely unknown. Specifically, in the absence of extracellular divalent cations, it becomes permeable to monovalent cations with a larger conductance, however, this monovalent cation current inactivates rapidly by an unknown mechanism. Here we found that Ca2+ dissociation from a site on the extracellular side of the CRAC channel is responsible for the inactivation of its Na+ current, and Ca2+ occupancy of this site otherwise potentiates its Ca2+ as well as Na+ currents. This Ca2+-dependent potentiation is required for the normal functioning of CRAC channels.
Current is a flow of electrical charge carriers, usually electrons or electron-deficient atoms.
If something becomes magnetized for a short amount of time it is only a matter of time before it isn't magnetic anymore. permeant on the other hand is forever and will never undo itself.
The process of oxidation is where electrons are lost. Thus, out of the 2 ions that change charge(Cr and Cu), we must choose the one where the oxidation number increases(which means electrons are lost). Cr goes from an oxidation number of 0 to an oxidation number of 3+, while Cu goes from an oxidation number of 2+ to 0. Thus, we are looking at the half reaction for Cr. Half reactions never have subtracting electrons, so the answer must be B. I am assuming that last plus should be a -->