Ca2+-Sensitive Potassium Channels

Abstract

The Ca2+ ion is used ubiquitously as an intracellular signaling molecule due to its high external and low internal concentration. Many Ca2+-sensing ion channel proteins have evolved to receive and propagate Ca2+ signals. Among them are the Ca2+-activated potassium channels, a large family of potassium channels activated by rises in cytosolic calcium in response to Ca2+ influx via Ca2+-permeable channels that open during the action potential or Ca2+ release from the endoplasmic reticulum. The Ca2+ sensitivity of these channels allows internal Ca2+ to regulate the electrical activity of the cell membrane. Activating these potassium channels controls many physiological processes, from the firing properties of neurons to the control of transmitter release. This review will discuss what is understood about the Ca2+ sensitivity of the two best-studied groups of Ca2+-sensitive potassium channels: large-conductance Ca2+-activated K+ channels, KCa1.1, and small/intermediate-conductance Ca2+-activated K+ channels, KCa2.x/KCa3.1.

Exercise-induced adaptation of neurons in the vertebrate locomotor system

“…Small conductance K(Ca) channels are activated by cytosolic calcium in response to calcium influx via voltage-gated calcium channels during AP generation. 62 , 88 , 89 K(Ca) channels control many physiological processes, from the firing properties of neurons to the control of neurotransmitter release. 90 During repetitive firing, the inter-spike interval is dependent on the amplitude and duration of the AHP.…”

Exploring the Impact of BKCa Channel Function in Cellular Membranes on Cardiac Electrical Activity

“…BKCa channels are members of the KV channel family, distinguished by their unique mode of activation. Activation of these channels occurs through an allosteric mechanism triggered by alterations in intracellular Ca 2+ levels, variations in membrane potentials, or a combination of both factors [1][2][3][4]. Upon random activation, BKCa channels facilitate the flow of substantial amounts of ions, specifically favoring highly selective K + ions, through the cell membrane.…”

KCa2.2 (KCNN2): A physiologically and therapeutically important potassium channel

“…K Ca 2.x channels are voltage-independent but are activated by increases in intracellular Ca 2+ with a half-maximal activation in the 300-800 nM range (Brown et al, 2020). They are named small-conductance Ca 2+ -activated potassium channels due to their comparatively low single-channel conductance which is about 10 pS compared to the intermediate channels conductance (20-60 pS) K + channels (IK or K Ca 3.1), and the large-conductance (150-300 pS) K + channels (K Ca 1.1 or BK Ca ) (Orfali & Albanyan, 2023;Skibsbye et al, 2014;Zheng & Trudeau, 2023).…”

“…Small‐conductance Ca 2+ ‐activated potassium channels (K Ca 2.x or SK channels) are widely expressed in neurons as well as the heart, endothelial cells, and other cell types (Köhler et al, 1996; Orfali & Albanyan, 2023; Skibsbye et al, 2014; Weisbrod et al, 2016). K Ca 2.x channels are voltage‐independent but are activated by increases in intracellular Ca 2+ with a half‐maximal activation in the 300–800 nM range (Brown et al, 2020).…”