Channelpedia

Kv9.2

Description: potassium voltage-gated channel, delayed-rectifier, subfamily S, member 2
Gene: Kcns2
Alias: Kv9.2, kcns2

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Introduction

Kv9.2, encoded by HCNS2, is a member 2 of subfamily S of potassium voltage-gated delayed-rectifier channels. Kv9.2 is not functional by itself but can form heteromultimers with member 1 and with member 2 (and possibly other members) of the Shab-related subfamily of potassium voltage-gated channel proteins. NCBI [606]


Experimental data

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Gene

In contrast to the genes in the other subfamilies, members of the Kv8 and Kv9 subfamilies have been found to be incapable of forming functional channels when expressed either in oocytes or cell lines. Moreover, these mammalian genes appear to have no Drosophila homologs. [402]

Species NCBI gene ID Chromosome Position
Human 3788 8 5895
Mouse 16539 15 6052
Rat 66022 7 6070

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Transcript

Species NCBI accession Length (nt)
Human NM_020697.4 5288
Mouse NM_181317.4 5473
Rat NM_023966.2 5476

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Protein Isoforms

Species Uniprot ID Length (aa)
Human Q9ULS6 477
Mouse O35174 477
Rat Q9ER26 477

Isoforms

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

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Post-Translational Modifications

PTM
Position
Type

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Structure

Kv9.2
Visual Representation of Kv9.2 Structure
Methodology for visual representation of structure available here

Structure of Kv9.2 ion Channel

The ORFs of Kv9.1 and Kv9.2 encode proteins of 497 and 477 amino acids, respectively, with a calculated molecular mass of 54.9 and 54.3 kDa (Fig. 1 A). Protein sequences reveal that all the structural characteristics of outward rectifier voltage-gated K+ channel α subunits (Kv) are conserved in Kv9.1 and Kv9.2, i.e. six putative transmembrane segments (S1 to S6), a transmembrane region (S4) showing five positively charged amino acids and a conserved pore-forming region (named H5 or P domain). As indicated in Fig. 1 A, Kv9.1 and Kv9.2 subunits contain several putative phosphorylation sites located in the cytoplasmic regions for protein kinase C, cAMP-dependent protein kinase, Ca2+-calmodulin kinase II, casein kinase II, and tyrosine kinase. No N-glycosylation sequence was detected [400]

Kv9.2 predicted AlphaFold size

Species Area (Å2) Reference
Human 3754.68 source
Mouse 5659.09 source
Rat 3402.95 source

Methodology for AlphaFold size prediction and disclaimer are available here


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Kinetics

Kinetics of Kv9.2 with Kv2 Family

Kv1.1 structure The time constant of activation of Kv2.1 was not modified by Kv9.1 but it was slightly increased by Kv9.2. No variation of the intensity of the remaining Kv2.1 current after a 9-s inactivation was recorded in the presence of Kv9.1 and Kv9.2. The image bellow shows that the normalized Kv2.2 currents are only slightly modified by Kv9.1 and Kv9.2. The time constant of activation of Kv2.2 was slightly decreased by Kv9.1 and not modified by Kv9.2 [400].


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Expression and Distribution

Kv9.2 Expressed Exclusively in the Brain

Northern blot analysis presented in Fig.2 shows that Kv9.1 and Kv9.2 mRNAs are expressed only in the brain. Specific probes detected two transcripts for Kv9.1 with an estimated size of 2.2 and 2.7 kb and one for Kv9.2 of approximately 5.3 kb. No expression was observed in heart, spleen, lung, liver, skeletal muscle, kidney, or testis [4000]

Inferior Colliculus

Kv9.1 and Kv9.2, two known members of the Kv9 subfamily, appear to be expressed diffusely in cells of the inferior colliculus [400].


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Function

Kv9.1 and Kv9.2 are neuronal modulatory alpha subunits that define a structural family designated as Kv9. They modulate Kv2.alpha subunits but have no functional activity by themselves. [400]. I.e., the kinetics of activation and the voltage-dependence of Kv2.1 currents are altered by such co-expression with Kv9.1 [402].

K+ channel functions are included in very diverse processes such as neuronal integration, cardiac pacemaking, muscle contraction, and hormone secretion in excitable cells [735], as well as in cell proliferation, cell volume regulation, and lymphocyte differentiation [736].


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Interaction

Kv2.1 and Kv2.2

Kv9.1 and Kv9.2 colocalized with Kv2.1 and/or Kv2.2 α subunits in several regions of the brain and alters the Kv2's kinetics as well [400]


References

400

Salinas M et al. New modulatory alpha subunits for mammalian Shab K+ channels.
J. Biol. Chem., 1997 Sep 26 , 272 (24371-9).

402

733

734

736

Lewis RS et al. Potassium and calcium channels in lymphocytes.
Annu. Rev. Immunol., 1995 , 13 (623-53).

737

Pongs O Structure-function studies on the pore of potassium channels.
J. Membr. Biol., 1993 Oct , 136 (1-8).

738

Heginbotham L et al. Mutations in the K+ channel signature sequence.
Biophys. J., 1994 Apr , 66 (1061-7).

739

MacKinnon R Pore loops: an emerging theme in ion channel structure.
Neuron, 1995 May , 14 (889-92).

740

Pascual JM et al. K+ pore structure revealed by reporter cysteines at inner and outer surfaces.
Neuron, 1995 May , 14 (1055-63).

741


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Credits

Contributors: Rajnish Ranjan, Michael Schartner, Katherine Johnston

To cite this page: [Contributors] Channelpedia https://channelpedia.epfl.ch/wikipages/31/ , accessed on 2024 Dec 02



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