Abstract
PDF (544 K)
E-mail Article
Add to my Quick Links
Cited By in Scopus (265)
200 nm in young rats (3–5 month old Fisher 344 rats) which remains normal in old (25–30 month rats) cerebral myocytes. Consistent with a healthy MaxiK channel expression in old cerebral arteries, MaxiK current density, kinetics and Ca2+ sensitivity were practically identical in young and old myocytes. Sensitivity to nanomolar concentrations of dehydrosoyasaponin-I that activates channels formed by α and β subunits is also the same in young and old myocytes. These results demonstrate that MaxiK channels maintain normal expression during cerebral aging which is in sharp contrast to our previous finding of loss of expression in aging coronary arteries. It seems therefore, that cerebral myocytes have developed a protective anti-aging mechanism leading to the continued expression of MaxiK channels.
doi:10.1016/0896-6273(95)90321-6 
Copyright © 1995
Article
Functional role of the β subunit of high conductance calcium-activated potassium channels
Owen B. McManusa, Lisa M. H. Helmsa, Leo Pallanckc, Barry Ganetzkyc, Richard Swansonb and Reid J. Leonarda
a Department of Membrane Biochemistry and Biophysics, USA
b Department of Pharmacology Merck Research Labs, Rahway, New Jersey 07065, USA
c Laboratory of Genetics University of Wisconsin, Madison, Wisconsin 53706, USA
Received 30 November 1994;
Abstract
Mammalian high conductance, calcium-activated potassium (maxi-K) channels are composed of two dissimilar subunits, α and β. We have examined the functional contribution of the β subunit to the properties of maxi-K channels expressed heterologously in Xenopus oocytes. Channels from oocytes injected with cRNAs encoding both a and β subunits were much more sensitive to activation by voltage and calcium than channels composed of the α subunit alone, while expression levels, single-channel conductance, and ionic selectivity appeared unaffected. Channels from oocytes expressing both subunits were sensitive to DHS-I, a potent agonist of native maxi-K channels, whereas channels composed of the α subunit alone were insensitive. Thus, α and β subunits together contribute to the functional properties of expressed maxi-K channels. Regulation of coassembly might contribute to the functional diversity noted among members of this family of potassium channels.
References
Adelman, J.P., Shen, K.-Z., Kavanaugh, M.P., Warren, R.A., Wu, Y.-N., Lagrutta, A., Bond, C.T. and North, R.A., 1992. Calciumactivated potassium channels expressed from cloned complementary DNAs. Neuron 9, pp. 209–216. Abstract | Article | 
PDF (917 K)
| View Record in Scopus | Cited By in Scopus (265)
Atkinson, N.S., Robertson, G.A. and Ganetzky, B., 1991. A component of calcium-activated potassium channels encoded by the Drosophila slo locus. Science 253, pp. 551–553.
Butler, A., Tsunoda, S., McCobb, D.P., Wei, A. and Salkoff, L., 1993. mSlo, a complex mouse gene encoding “maxi” calcium-activated potassium channels. Science 261, pp. 221–224. View Record in Scopus | Cited By in Scopus (337)
Candia, S., Garcia, M.L. and Latorre, R., 1993. Iberiotoxin: a potent blocker of the large-conductance Ca+-activated K+ channel. Biophys. J. 63, pp. 583–590.
Gaavez, A., Gimenez-Gallego, G., Reuben, J.P., Roy-Contancin, L., Feigenbaum, P., Kaczorowski, G.J. and Garcia, M.L., 1990. Purification and characterization of a unique, potent, peptidyl probe for the high conductance calcium-activated potassium channel from venom of the scorpion Buthus tamulus. J. Biol. Chem. 265, pp. 11083–11090.
Garcia-Calvo, M., Knaus, H.-G., McManus, O.B., Giangiacomo, K.M., Kaczorowski, G.J. and Garcia, M.L., 1994. Purification and reconstitution of the high-conductance, calcium-activated potassium channel from tracheal smooth muscle. J. Biol. Chem. 269, pp. 676–682. View Record in Scopus | Cited By in Scopus (110)
Giangiacomo, K.M., Garcia, M.L. and McManus, O.B., 1992. Mechanism of iberiotoxin block of the large-conductance calcium-activated potassium channel from bovine aortic smooth muscle. Biochemistry 31, pp. 6719–6727. View Record in Scopus | Cited By in Scopus (83)
Hamill, O.P., Marty, A., Neher, E., Sakmann, B. and Sigworth, F.J., 1981. Improved patch clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflügers Arch. 391, pp. 85–100. View Record in Scopus | Cited By in Scopus (7650)
Isom, L.L., De, Jongh K.S. and Catterall, W.A., 1994. Auxilary subunits of voltage-gated ion channels. Neuron 12, pp. 1183–1194. Abstract | Article | PDF (1299 K)
| View Record in Scopus | Cited By in Scopus (327)
Knaus, H.-G., Folander, K., Garcia-Calvo, M., Garcia, M.L., Kaczorowski, G.J., Smith, M. and Swanson, R., 1994. Primary sequence and immunological characterization of the beta subunit of the highconductance Ca 2+-activated K+ channel from smooth muscle. J. Biol. Chem. 269, pp. 17274–17278. View Record in Scopus | Cited By in Scopus (175)
Knaus, H.-G., Garcia-Calvo, M., Kaczorowski, G.J. and Garcia, M.L., 1994. Subunit composition of the high-conductance calciumactivated potassium channel from smooth muscle, a representitive of the mslo and slowpoke family of potassium channels. J. Biol. Chem. 269, pp. 3921–3924. View Record in Scopus | Cited By in Scopus (99)
Latorre, R., Oberhauser, A., Labarca, P. and Alvarez, O., 1989. Varieties of calcium-activated potassium channels. Annu. Rev. Physiol. 51, pp. 385–399. View Record in Scopus | Cited By in Scopus (361)
McManus, O.B., 1991. Calcium-activated potassium channels: regulation by calcium. J. Bioenerg. Biomembr. 23, pp. 537–560. View Record in Scopus | Cited By in Scopus (152)
McManus, O.B. and Magleby, K.L., 1991. Accounting for the Ca2+-dependent kinetics of single large-conductance Ca2+-activated K+ channels in rat skeletal muscle. J. Physiol. 443, pp. 739–777. View Record in Scopus | Cited By in Scopus (90)
McManus, O.B., Harris, G.H., Giangiacomo, K.M., Feigenbaum, P., Reuben, J.P., Addy, M.E., Burka, J.F., Kaczorowski, G.J. and Garcia, M.L., 1993. An activator of calcium-dependent potassium channels isolated from a medicinal herb. Biochemistry 32, pp. 6128–6133. View Record in Scopus | Cited By in Scopus (92)
Moczydlowski, E. and Latorre, R., 1983. Gating kinetics of Ca2+-activated K+ channels from rat muscle incorporated into planar lipid bilayers: evidence for two voltage-dependent Ca+ binding reactions. J. Gen. Physiol. 82, pp. 511–542. View Record in Scopus | Cited By in Scopus (94)
Pallanck, L. and Ganetzky, B., 1994. Cloning and characterization of human and mouse homologues of the Drosophila calcium-activated potassium channel gene, slowpoke. Hum. Mol. Genet. 3, pp. 1239–1243. View Record in Scopus | Cited By in Scopus (110)
Perez, G., Lagrutta, A., Adelman, J.P. and Toro, L., 1994. Reconstitution of expressed KCa channels from Xenopus oocytes to lipid bilayers. Biophys. J. 66, pp. 1022–1027. View Record in Scopus | Cited By in Scopus (29)
Rettig, J., Heinemann, S.H., Wunder, F., Lorra, C., Parcej, D.N., Dolly, J.O. and Pongs, O., 1994. Inactivation properties of voltage-gated K+ channels altered by presence of beta subunit. Nature 369, pp. 289–294. View Record in Scopus | Cited By in Scopus (506)
