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Slo2

potassium channel, subfamily T, member 1
Synonyms: Slo2 kcnt1 KCa4.1 SLACK. Symbol: Kcnt1

Introductions


Two genes, Slack (also known as kcnt1 or Slo2.2) and Slick (also known as kcnt 2 or Slo 2.1) encode outwardly rectifying potassium channels that are activated by intracellular Na+ (Bhattacharjee et al., 2003 [1137]; Joiner et al., 1998 [1138]; Yuan et al., 2003 [1139]). When expressed in heterologous expression systems, Slick currents differ from Slack currents, in that they exhibit instantaneous activation kinetics (Bhattacharjee et al., 2003 [1137]; Santi et al., 2006 [161]); Slack currents on the other hand exhibit slower activation kinetics in response to depolarization (Bhattacharjee et al., 2003 [1137]; Joiner et al., 1998 [1138]).

Genes


The gene Kcnt1 (also known as slo2; Slack; mKIAA1422; C030030G16Rik) encodes slo2, a potassium channel, subfamily T, member 1. http://www.ncbi.nlm.nih.gov/gene/227632

Kcnt1 : potassium channel, subfamily T, member 1

RGD ID Chromosome Position Species
621106 3 4050340-4088029 Rat
1622971 2 25719374-25773793 Mouse
734382 9 138594031-138684993 Human

Transcripts


Acc No Sequence Length Source
NM_021853 NCBI
NM_175462 NCBI
NM_001145403 NCBI
NM_020822 NCBI

Ontologies


Accession Name Definition Evidence
GO:0016021 integral to membrane Penetrating at least one phospholipid bilayer of a membrane. May also refer to the state of being buried in the bilayer with no exposure outside the bilayer. When used to describe a protein, indicates that all or part of the peptide sequence is embedded in the membrane. IDA
GO:0005886 plasma membrane The membrane surrounding a cell that separates the cell from its external environment. It consists of a phospholipid bilayer and associated proteins. IEA
GO:0016020 membrane Double layer of lipid molecules that encloses all cells, and, in eukaryotes, many organelles; may be a single or double lipid bilayer; also includes associated proteins. IEA

Interactions


Both Slack and Slick have numerous consensus phosphorylation sites within their respective carboxy termini and modulation of Na+ binding and subsequent gating could be feasible through phosphorylation or dephosphorylation-induced conformational changes. Indeed, the modulation of Slack and Slick by protein kinase C (PKC) has previously been determined (Santi et al., 2006 [1139]). Slack and Slick contain both overlapping and unique consensus PKC phosphorylation sites (Bhattacharjee et al., 2003 [1141]; Joiner et al., 1998 [1138]) and it was shown that activation of PKC by phorbol esters caused an inhibition of Slick currents whereas Slack currents were facilitated after PKC activation (Santi et al., 2006 [1139]). Moreover, Slick and Slack channels were colocalized with G-alpha-q–protein coupled receptors in certain neurons (Santi et al., 2006 [1139]) suggesting that PKC modulation is likely to also occur in native neurons. (Nuwer [159])

Proteins


Structures


The homology between Slack and Slick is high, especially within the putative six transmembrane domains and proximal carboxy terminal (Bhattacharjee et al., 2003 [1141]). Both channels resemble the Ca2+-activated K+ ‘Slowpoke’ (Slo) channel by containing very large carboxy termini in addition to the transmembrane domains (Salkoff et al., 2006 [1140]). The large carboxy termini of Slack, Slick and Slo contain "regulate the conductance of K+ (RCK) domains" (Bhattacharjee and Kaczmarek, 2005 [1137]; Salkoff et al., 2006 [1140]). These RCK domains are thought to be essential for ligand binding and concomitant gating for this class of potassium channel (Jiang et al., 2002 [625]; Ye et al., 2006 [1142]).

Distributions


Expressions


Slo2 is widely expressed in the rat brain. For a detailed table about the expression of Slo2 (Slack) see table 1 in Bhattacharjee and Kaczmarek, 2005 [1137].

Functionals


Kinetics


In symmetrical KC conditions, Slack channels have an EC50 of 41 mM for activation by Na+ and a unitary conductance of 180 pS, with multiple subconductance states (Yuan [1139], Bhattacharjee [1141]). Interestingly, given the lack of positive charges in S4, Slack channels are voltagedependent (Joiner [1138]). Slack currents are outwardly rectifying and, in response to depolarization, they typically have an instantaneous component followed by a slow time-dependent increase in current (i.e. a ‘slow-gate’) (Joiner [1138], Bhattacharjee [1141]). The kinetic properties of Slack channels suggest that they could contribute to currents that develop slowly during maintained neuronal firing. (Bhattacharjee [1137]

Models


References


[159 : 19540251]
[160 : 18787033]
[162 : 16876206]
[1137 : 15979166]
[1138 : 10196543]
[1139 : 12628167]
[161 : 16687497]
[1140 : 17115074]
[1141 : 14684870]
[625 : 12037559]
[1142 : 16990139]

Credits