Channelpedia

Slo3

Description: potassium large conductance pH-sensitive channel, subfamily M, alpha member 3
Gene: Kcnu1
Alias: Slo3, kcnu1, Kcnma3, KCa5, Kcnma3, KCa5.1

Edit - History

Introduction

The mouse Slo3 gene (KCNMA3) encodes a K+ channel that is regulated by changes in cytosolic pH. Like Slo1 subunits responsible for the Ca2+ and voltage-activated BK-type channel, the Slo3 α subunit contains a pore module with homology to voltage-gated K+ channels and also an extensive cytosolic C terminus thought to be responsible for ligand dependence. For the Slo3 K+ channel, increases in cytosolic pH promote channel activation, but very little is known about many fundamental properties of Slo3 currents. (Zhang [165])


Edit - History

Gene

Slo3 shares the most extensive sequence homology with Slo1 (Schreiber 1998 [1160]).

Species NCBI gene ID Chromosome Position
Human 157855 8 151751
Mouse 16532 8 89315
Rat 680912 16 87797

Edit

Transcript

Species NCBI accession Length (nt)
Human NM_001031836.3 3692
Mouse NM_008432.3 3548

Edit

Protein Isoforms

Species Uniprot ID Length (aa)
Human A8MYU2 1149
Mouse O54982 1121
Rat D4A6Z8 1113

Isoforms

Transcript
Length (nt)
Protein
Length (aa)
Variant
Isoform

Edit

Post-Translational Modifications

PTM
Position
Type

Edit - History

Structure

K+ channels formed from α subunits encoded by the Slo gene family (Adelman et al., 1992 [1156]; Butler et al., 1993 [1157]) are characterized by a large cytosolic C-terminal structure that is thought to be involved in ligand-dependent regulation of the channels (Wei et al., 1994 [1158]; Schreiber and Salkoff [1159], 1997; Schreiber et al. , 1998 [1160]; Bhattacharjee et al., 2002 [1161]; Jiang et al., 2002 [625]; Shi et al., 2002 [1131]; Xia et al., 2002 [1136]; Bhattacharjee et al., 2003 [1141]; Yuan et al., 2003 [1139]; Xia et al., 2004 [164]). In fact, the hallmark for each member of the Slo family appears to be regulation by a specific cytosolic ligand: pH for Slo3 (Schreiber et al., 1998 [1160]; Xia et al., 2004 [164]).

Slo3 predicted AlphaFold size

Species Area (Å2) Reference
Human 8048.59 source
Mouse 7861.39 source
Rat 7379.14 source

Methodology for AlphaFold size prediction and disclaimer are available here


Edit - History

Kinetics

Slo1 and Slo3 differ in two primary ways: first, the intrinsic voltage dependence of the Slo3 closed–open equilibrium is weaker, and, second, voltage sensor movement in Slo3 is much more weakly coupled to channel opening. Both activation and deactivation are best described by two exponential components, both of which are only weakly voltage dependent. Qualitatively, the properties of the two kinetic components in the activation time course suggest that increases in pH increase the fraction of more rapidly opening channels. (Zhang [165])


Edit - History

Expression and Distribution

In contrast to the wide distribution of channels arising from either Slo1 and Slo2.x subunits, Slo3 has a much more limited pattern of expression than the other family members, being found predominantly in mouse testis (Schreiber et al., 1998 [1160]).


Edit - History

Interaction

In contrast to Slo1, Slo3 is insensitive to cytosolic Ca2+ and appears sensitive to cytosolic pH (Schreiber et al., 1998 [1160]; Xia et al., 2004 [164]).


References

165

Zhang X et al. Slo3 K+ channels: voltage and pH dependence of macroscopic currents.
J. Gen. Physiol., 2006 Sep , 128 (317-36).

625

Jiang Y et al. Crystal structure and mechanism of a calcium-gated potassium channel.
Nature, 2002 May 30 , 417 (515-22).

Shi J et al. Mechanism of magnesium activation of calcium-activated potassium channels.
Nature, 2002 Aug 22 , 418 (876-80).

Bhattacharjee A et al. Slick (Slo2.1), a rapidly-gating sodium-activated potassium channel inhibited by ATP.
J. Neurosci., 2003 Dec 17 , 23 (11681-91).

Schreiber M et al. Transplantable sites confer calcium sensitivity to BK channels.
Nat. Neurosci., 1999 May , 2 (416-21).

Schreiber M et al. Slo3, a novel pH-sensitive K+ channel from mammalian spermatocytes.
J. Biol. Chem., 1998 Feb 6 , 273 (3509-16).

Bhattacharjee A et al. Localization of the Slack potassium channel in the rat central nervous system.
J. Comp. Neurol., 2002 Dec 16 , 454 (241-54).


Edit

Credits

To cite this page: [Contributors] Channelpedia https://channelpedia.epfl.ch/wikipages/71/ , accessed on 2024 Dec 02



Add section