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The large conductance Ca2+ -activated potassium channel (pSlo) of the cockroach Periplaneta americana: structure, localization in neurons and electrophysiology.

The large conductance Ca2+ -activated potassium channel (pSlo) of the cockroach Periplaneta americana: structure, localization in neurons and electrophysiology.

Authors :
Derst, C.
Messutat, S.
Walther, C.
Eckert, M.
Heinemann, S. H.
Wicher, D.
Source :
European Journal of Neuroscience; Mar2003, Vol. 17 Issue 6, p1197-1212, 0p, 1 Chart
Publication Year :
2003

Abstract

Abstract Voltage-activated, Ca<superscript>2+</superscript> -sensitive K<superscript>+</superscript> channels (BK or maxi K,Ca channels) play a major role in the control of neuronal excitability. We have cloned pSlo, the BK channel α subunit of the cockroach Periplaneta americana . The amino acid sequence of pSlo shows 88% identity to dSlo from Drosophila . There are five alternatively spliced positions in pSlo showing differential expression in various tissues. A pSlo-specific antibody prominently stained the octopaminergic dorsal unpaired median (DUM) neurons and peptidergic midline neurons in Periplaneta abdominal ganglia. HEK293 cells expressing pSlo exhibit K<superscript>+</superscript> channels of 170 pS conductance. They have a tendency for brief closures, exhibit subconductance states and show slight inward rectification. Activation kinetics and voltage dependence are controlled by cytoplasmic [Ca<superscript>2+</superscript> ]. In contrast to dSlo, pSlo channels are sensitive to charybdotoxin and iberiotoxin. Mutagenesis at two positions (E254 and Q285) changed blocking efficacy of charybdotoxin. In contrast to pSlo expressed in HEK293 cells, native IbTx-sensitive K,Ca currents in DUM and in peptidergic neurons, exhibited rapid, partial inactivation. The fast component of the K,Ca current partly accounts for the repolarization and the early after-hyperpolarization of the action potential. By means of Ca<superscript>2+</superscript> -induced repolarization, BK channels may reduce the risk of Ca<superscript>2+</superscript> overload in cockroach neurons. Interestingly, the neurons expressing pSlo were also found to express taurine, a messenger that is likely to limit overexcitation by an autocrine mechanism in mammalian central neurons. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
0953816X
Volume :
17
Issue :
6
Database :
Complementary Index
Journal :
European Journal of Neuroscience
Publication Type :
Academic Journal
Accession number :
9457090
Full Text :
https://doi.org/10.1046/j.1460-9568.2003.02550.x