Biophysical Journal 70: 2640-2651 (1996)
© 1996 the Biophysical Society

This Article Full Text (PDF) A correction has been published A correction has been published Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Silberberg, S D Articles by Magleby, K L Search for Related Content PubMed PubMed Citation Articles by Silberberg, S D Articles by Magleby, K L

Wanderlust kinetics and variable Ca(2+)-sensitivity of Drosophila, a large conductance Ca(2+)-activated K+ channel, expressed in oocytes.

Department of Life Sciences, Ben Gurion University of the Negev, Beer-Sheva, Israel.

ABSTRACT

Cloned large conductance Ca(2+)-activated K+ channels (BK or maxi-K+ channels) from Drosophila (dSlo) were expressed in Xenopus oocytes and studied in excised membrane patches with the patch-clamp technique. Both a natural variant and a mutant that eliminated a putative cyclic AMP-dependent protein kinase phosphorylation site exhibited large, slow fluctuations in open probability with time. These fluctuations, termed "wanderlust kinetics," occurred with a time course of tens of seconds to minutes and had kinetic properties inconsistent with simple gating models. Wanderlust kinetics was still observed in the presence of 5 mM caffeine or 50 nM thapsigargin, or when the Ca2+ buffering capacity of the solution was increased by the addition of 5 mM HEDTA, suggesting that the wanderlust kinetics did not arise from Ca2+ release from caffeine and thapsigargin sensitive internal stores in the excised patch. The slow changes in kinetics associated with wanderlust kinetics could be generated with a discrete-state Markov model with transitions among three or more kinetic modes with different levels of open probability. To average out the wanderlust kinetics, large amounts of data were analyzed and demonstrated up to a threefold difference in the [Ca2+]i required for an open probability of 0.5 among channels expressed from the same injected mRNA. These findings indicate that cloned dSlo channels in excised patches from Xenopus oocytes can exhibit large variability in gating properties, both within a single channel and among channels.

This article has been cited by other articles:

				Z. Guo, C. Lv, H. Yi, Y. Xiong, Y. Wu, W. Li, T. Xu, and J. Ding A Residue at the Cytoplasmic Entrance of BK-Type Channels Regulating Single-Channel Opening by Its Hydrophobicity Biophys. J., May 1, 2008; 94(9): 3714 - 3725. [Abstract] [Full Text] [PDF]

				W. Li and R. W. Aldrich State-dependent Block of BK Channels by Synthesized Shaker Ball Peptides J. Gen. Physiol., October 1, 2006; 128(4): 423 - 441. [Abstract] [Full Text] [PDF]

				G. Krishnamoorthy, J. Shi, D. Sept, and J. Cui The NH2 Terminus of RCK1 Domain Regulates Ca2+-dependent BKCa Channel Gating J. Gen. Physiol., August 29, 2005; 126(3): 227 - 241. [Abstract] [Full Text] [PDF]

				Y. Zhou, J. Wang, H. Wen, O. Kucherovsky, and I. B. Levitan Modulation of Drosophila Slowpoke Calcium-Dependent Potassium Channel Activity by Bound Protein Kinase A Catalytic Subunit J. Neurosci., May 15, 2002; 22(10): 3855 - 3863. [Abstract] [Full Text] [PDF]

				S. Herzig and J. Neumann Effects of Serine/Threonine Protein Phosphatases on Ion Channels in Excitable Membranes Physiol Rev, January 1, 2000; 80(1): 173 - 210. [Abstract] [Full Text] [PDF]

				A. Meir, S. Ginsburg, A. Butkevich, S. G. Kachalsky, I. Kaiserman, R. Ahdut, S. Demirgoren, and R. Rahamimoff Ion Channels in Presynaptic Nerve Terminals and Control of Transmitter Release Physiol Rev, July 1, 1999; 79(3): 1019 - 1088. [Abstract] [Full Text] [PDF]

				L. Diaz, P. Meera, J. Amigo, E. Stefani, O. Alvarez, L. Toro, and R. Latorre Role of the S4 Segment in a Voltage-dependent Calcium-sensitive Potassium (hSlo) Channel J. Biol. Chem., December 4, 1998; 273(49): 32430 - 32436. [Abstract] [Full Text] [PDF]

				A. Alioua, Y. Tanaka, M. Wallner, F. Hofmann, P. Ruth, P. Meera, and L. Toro The Large Conductance, Voltage-dependent, and Calcium-sensitive K+ Channel, Hslo, Is a Target of cGMP-dependent Protein Kinase Phosphorylation in Vivo J. Biol. Chem., December 4, 1998; 273(49): 32950 - 32956. [Abstract] [Full Text] [PDF]

				T. J. DiChiara and P. H. Reinhart Redox Modulation of hslo Ca2+-Activated K+ Channels J. Neurosci., July 1, 1997; 17(13): 4942 - 4955. [Abstract] [Full Text] [PDF]

				E. Stefani, M. Ottolia, F. Noceti, R. Olcese, M. Wallner, R. Latorre, and L. Toro Voltage-controlled gating in a large conductance Ca2+-sensitive K+channel (hslo) PNAS, May 13, 1997; 94(10): 5427 - 5431. [Abstract] [Full Text] [PDF]

				J. Wang, Y. Zhou, H. Wen, and I. B. Levitan Simultaneous Binding of Two Protein Kinases to a Calcium-Dependent Potassium Channel J. Neurosci., May 15, 1999; 19(10): RC4 - RC4. [Abstract] [Full Text] [PDF]

				G. M. Dick and K. M. Sanders (Xeno)estrogen Sensitivity of Smooth Muscle BK Channels Conferred by the Regulatory beta 1 Subunit. A STUDY OF beta 1 KNOCKOUT MICE J. Biol. Chem., November 21, 2001; 276(48): 44835 - 44840. [Abstract] [Full Text] [PDF]