Abstract
Single calcium dependent potassium channels from cultured rat myoballs have been studied with the patch clamp technique, and current records subjected to statistical analysis. From the dependence of the mean open state probability on the internal calcium concentration, two calcium ions are required to open the channel. The open state and closed state lifetime distributions reveal that the usual activation model is not applicable to these channels. They are consistent with a two step gating mechanism that involves both activation by calcium and blockade by a calcium-sensitive gate.
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References
Adams PR (1981) Acetylcholine receptor kinetics. J Membrane Biol 58:161–174
Adams PR, Constanti A, Brown DA, Clark RB (1982) Intracellular Ca2+ activates a fast voltage-sensitive K+ current in vertebrate sympathetic neurones. Nature 296:746–749
Barrett JN, Magleby KL, Pallotta BS (1982) Properties of single calcium-activated potassium channels. J Physiol (in press)
Boheim G, Methfessel C, Sakmann B (1982) Ca++ activates K+ channel by preventing channel blockade. Pflügers Arch 392:R19
Colquhoun D, Hawkes AG (1977) Relaxation and fluctuations of membrane currents that flow through drug operated channels. Proc R Soc London B199:231–262
Colquhoun D, Sakmann B (1981) Fluctuations in the microsecond time range of the current through single acetylcholine receptor ion channels. Nature 294:464–466
Cull-Candy SG, Miledi R, Parker I (1981) Single glutamate-activated channels recorded from locust muscle fibres with perfused patch-clamp electrodes. J Physiol 321:195–210
Cull-Candy SG, Parker I (1982) Rapid kinetics of single glutamate-receptor channels. Nature 295:410–412
Fink R, Hase S, Lüttgau HC, Wettwer E (1983) The effect of cellular energy reserves and internal Ca++ on the potassium conductance in skeletal muscle of the frog. J Physiol (in press)
Gration KAF, Lambert JJ, Ramsey R, Usherwood PNR (1981) Nonrandom openings and concentration-dependent lifetimes of glutamate-gated channels in muscle membrane. Nature 291:423–425
Hagiwara S, Nakajima S (1966) Effects of the intracellular Ca ion concentration upen the excitability of the muscle fiber membrane of a Barnacle. J Gen Physiol 49:807–818
Hamill OP, Marty A, Neher E, Sakmann B, Sigworth FJ (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch 391:85–100
Heidmann T, Changeux JP (1978) Structural and functional properties of the acetylcholine receptor protein in its purified and membrane-bound states. Annu Rev Biochem 47:317–357
Katz B (1966) Nerve, muscle and synapse. McGraw-Hill, New York
Kemeny JG, Snell JL (1976) Finite Markov chains. Springer, Berlin Heidelberg New York
Latorre R, Vergara C, Hidalgo C (1982) Reconstitution in planar lipid bilayers of a Ca2+-dependent K+ channel from transverse tubule membranes isolated from rabbit skeletal muscle. Proc Natl Acad Sci USA 79:805–810
Lux HD, Neher E, Marty A (1981) Single channel activity associated with the calcium dependent outward current in helix pomatia. Pflügers Arch 389:293–295
Marty A (1981) Ca-dependent K channels with large unitary conductance in chromaffin cell membranes. Nature 291:497–500
Meech RW (1978) Calcium-dependent potassium activation in nervous tissues. Annu Rev Biophys Bioeng 7:1–18
Miller C, Rosenberg R (1979) Modification of a voltage-gated K+ channel from sarcoplasmic reticulum by a pronase-derived specific endopeptidase. J Gen Physiol 74:457–478
Neher E, Sakmann B, Steinbach JH (1978) The extracellular patch clamp:A method for resolving currents through individual open channels in biological membranes. Pflügers Arch 375:219–228
Neher E, Steinbach HJ (1978) Local anaesthetics transiently block currents through single acetylcholine-receptor channels. J Physiol 277:153–176
Pallotta BS, Magleby KL, Barrett JN (1981) Single channel recordings of Ca2+ activated K+ currents in rat muscle cell culture. Nature 293:471–474
Sakmann B, Hamill OP, Bormann J (1982) Activation of chloride channels by putative inhibitory transmitters in spinal cord neurons. Pflügers Arch 392:R19
Sakmann B, Patlak J, Neher E (1980) Single acetylcholine-activated channels show burst-kinetics in presence of desensitizing concentrations of agonist. Nature 286:71–73
Schwarz W, Passow H (1983) Ca-activated K+ channels in erythrocytes and excitable cells. Annu Rev Physiol (in press)
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Methfessel, C., Boheim, G. The gating of single calcium-dependent potassium channels is described by an activation/blockade mechanism. Biophys. Struct. Mechanism 9, 35–60 (1982). https://doi.org/10.1007/BF00536014
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DOI: https://doi.org/10.1007/BF00536014