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Protein

Two-pore potassium channel 1

Gene

TPK1

Organism
Arabidopsis thaliana (Mouse-ear cress)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

Voltage-independent, large conductance and potassium-selective tonoplast ion channel. Regulated by cytoplasmic calcium and pH. Does not mediate slow-vacuolar (SV) ionic currents, but essential to establish VK currents. Has some permeability for Rb+ and NH4+, but none for Na+, Cs+ or Li+. Involved in intracellular K+ redistribution and/or K+ retranslocation between different tissues.4 Publications

Enzyme regulationi

Could be activated by protein kinase C (By similarity). Strongly induced by calcium. Blocked by barium, tetraethylammonium (TEA), quinine and quinidine.By similarity2 Publications

Regions

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Calcium bindingi301 – 3121Sequence analysisAdd BLAST12
Calcium bindingi340 – 3512Sequence analysisAdd BLAST12

GO - Molecular functioni

  • ion channel activity Source: TAIR
  • metal ion binding Source: UniProtKB-KW
  • voltage-gated potassium channel activity Source: InterPro

GO - Biological processi

  • cellular potassium ion homeostasis Source: TAIR
  • protein homooligomerization Source: TAIR
  • regulation of seed germination Source: TAIR
  • regulation of stomatal movement Source: TAIR
Complete GO annotation...

Keywords - Molecular functioni

Ion channel, Potassium channel

Keywords - Biological processi

Ion transport, Potassium transport, Transport

Keywords - Ligandi

Calcium, Metal-binding, Potassium

Enzyme and pathway databases

BioCyciARA:AT5G55630-MONOMER.
MetaCyc:MONOMER-14554.

Protein family/group databases

TCDBi1.A.1.7.3. the voltage-gated ion channel (vic) superfamily.

Names & Taxonomyi

Protein namesi
Recommended name:
Two-pore potassium channel 1
Short name:
AtTPK1
Alternative name(s):
Calcium-activated outward-rectifying potassium channel 1
Short name:
AtKCO1
Gene namesi
Name:TPK1
Synonyms:KCO1
Ordered Locus Names:At5g55630
ORF Names:MDF20.7
OrganismiArabidopsis thaliana (Mouse-ear cress)
Taxonomic identifieri3702 [NCBI]
Taxonomic lineageiEukaryotaViridiplantaeStreptophytaEmbryophytaTracheophytaSpermatophytaMagnoliophytaeudicotyledonsGunneridaePentapetalaerosidsmalvidsBrassicalesBrassicaceaeCamelineaeArabidopsis
Proteomesi
  • UP000006548 Componenti: Chromosome 5

Organism-specific databases

TAIRiAT5G55630.

Subcellular locationi

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Topological domaini1 – 78CytoplasmicSequence analysisAdd BLAST78
Transmembranei79 – 99HelicalSequence analysisAdd BLAST21
Intramembranei111 – 130Pore-forming; Name=Pore-forming 1Sequence analysisAdd BLAST20
Transmembranei137 – 157HelicalSequence analysisAdd BLAST21
Topological domaini158 – 197CytoplasmicSequence analysisAdd BLAST40
Transmembranei198 – 218HelicalSequence analysisAdd BLAST21
Intramembranei225 – 244Pore-forming; Name=Pore-forming 2Sequence analysisAdd BLAST20
Transmembranei251 – 271HelicalSequence analysisAdd BLAST21
Topological domaini272 – 363CytoplasmicSequence analysisAdd BLAST92

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Membrane, Vacuole

Pathology & Biotechi

Disruption phenotypei

Reduced growth in both high and low K+ conditions. Slower germination and increased sensitivity to abscisic acid. Reduction of the total tonoplast current density.1 Publication

Mutagenesis

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Mutagenesisi42S → A: Loss of interaction with GRF6, but no effect on vacuolar targeting. 1 Publication1
Mutagenesisi296 – 298DLE → GLG: Retention in the endoplasmic reticulum. 1 Publication3
Mutagenesisi301 – 303DLD → GLG: No effect on vacuolar targeting. 1 Publication3

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00001017751 – 363Two-pore potassium channel 1Add BLAST363

Post-translational modificationi

Phosphorylation at Ser-42 increases and stabilizes the interaction with 14-3-3 proteins.1 Publication

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sitei131Not glycosylated1

Keywords - PTMi

Phosphoprotein

Proteomic databases

PaxDbiQ8LBL1.

PTM databases

iPTMnetiQ8LBL1.

Expressioni

Tissue specificityi

Detected in mesophyll cells, guard cells and vascular tissues of the leaves. Expressed in the hilum, where the funiculus is attached during fruit maturation and in the embryo. Also expressed at a lower level in seedlings, root tips and elongation zones, and flowers. Could be detected in mitotically active tissues.2 Publications

Gene expression databases

GenevisibleiQ8LBL1. AT.

Interactioni

Subunit structurei

Homodimer. Interacts with GRF1 and GRF6, but only GRF6 modulates the channel activity.3 Publications

Protein-protein interaction databases

BioGridi20901. 27 interactors.
STRINGi3702.AT5G55630.1.

Structurei

3D structure databases

ProteinModelPortaliQ8LBL1.
SMRiQ8LBL1.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini288 – 323EF-hand 1Add BLAST36
Domaini327 – 362EF-hand 2Add BLAST36

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi296 – 298Endoplasmic reticulum release signal3

Compositional bias

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Compositional biasi33 – 39Arg/Lys-rich (basic)7

Domaini

Each of the two pore-forming region (also called P-domain or P-loop) is enclosed by two transmembrane segments (2P/4TM) and contains the GYGD signature motif which seems to be involved in potassium selectivity. The C-terminus (328-363) is required for vacuolar targeting.

Sequence similaritiesi

Contains 2 EF-hand domains.Curated

Keywords - Domaini

Repeat, Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG1418. Eukaryota.
COG1226. LUCA.
HOGENOMiHOG000238193.
InParanoidiQ8LBL1.
KOiK05389.
OrthoDBiEOG09360EZI.
PhylomeDBiQ8LBL1.

Family and domain databases

Gene3Di1.10.238.10. 1 hit.
InterProiIPR003280. 2pore_dom_K_chnl.
IPR011992. EF-hand-dom_pair.
IPR018247. EF_Hand_1_Ca_BS.
IPR013099. K_chnl_dom.
IPR031144. TPK_plant.
[Graphical view]
PANTHERiPTHR11003:SF135. PTHR11003:SF135. 1 hit.
PfamiPF07885. Ion_trans_2. 2 hits.
[Graphical view]
PRINTSiPR01333. 2POREKCHANEL.
SUPFAMiSSF47473. SSF47473. 1 hit.
PROSITEiPS00018. EF_HAND_1. 2 hits.
[Graphical view]

Sequencei

Sequence statusi: Complete.

Q8LBL1-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MSSDAARTPL LPTEKIDTMA QDFNLNSRTS SSRKRRLRRS RSAPRGDCMY
60 70 80 90 100
NDDVKIDEPP PHPSKIPMFS DLNPNLRRVI MFLALYLTIG TLCFYLVRDQ
110 120 130 140 150
ISGHKTSGVV DALYFCIVTM TTVGYGDLVP NSSASRLLAC AFVFSGMVLV
160 170 180 190 200
GHLLSRAADY LVEKQEALLV RAFHLRQSFG PTDILKELHT NKLRYKCYAT
210 220 230 240 250
CLVLVVLFIV GTIFLVMVEK MPVISAFYCV CSTVTTLGYG DKSFNSEAGR
260 270 280 290 300
LFAVFWILTS SICLAQFFLY VAELNTENKQ RALVKWVLTR RITNNDLEAA
310 320 330 340 350
DLDEDGVVGA AEFIVYKLKE MGKIDEKDIS GIMDEFEQLD YDESGTLTTS
360
DIVLAQTTSQ IQR
Length:363
Mass (Da):40,727
Last modified:November 28, 2003 - v2
Checksum:i149B00AABBE40EFC
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti227F → V in AAM64705 (Ref. 6) Curated1
Sequence conflicti261S → T in CAA65988 (PubMed:9184204).Curated1
Sequence conflicti261S → T in CAA69158 (PubMed:12148538).Curated1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X97323 mRNA. Translation: CAA65988.1.
Y07825 Genomic DNA. Translation: CAA69158.1.
AB009050 Genomic DNA. Translation: BAB09230.1.
CP002688 Genomic DNA. Translation: AED96660.1.
CP002688 Genomic DNA. Translation: AED96661.1.
AK229302 mRNA. Translation: BAF01165.1.
AY087147 mRNA. Translation: AAM64705.1.
RefSeqiNP_200374.1. NM_124945.4.
NP_851196.1. NM_180865.1.
UniGeneiAt.20254.

Genome annotation databases

EnsemblPlantsiAT5G55630.1; AT5G55630.1; AT5G55630.
AT5G55630.2; AT5G55630.2; AT5G55630.
GeneIDi835657.
GrameneiAT5G55630.1; AT5G55630.1; AT5G55630.
AT5G55630.2; AT5G55630.2; AT5G55630.
KEGGiath:AT5G55630.

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
X97323 mRNA. Translation: CAA65988.1.
Y07825 Genomic DNA. Translation: CAA69158.1.
AB009050 Genomic DNA. Translation: BAB09230.1.
CP002688 Genomic DNA. Translation: AED96660.1.
CP002688 Genomic DNA. Translation: AED96661.1.
AK229302 mRNA. Translation: BAF01165.1.
AY087147 mRNA. Translation: AAM64705.1.
RefSeqiNP_200374.1. NM_124945.4.
NP_851196.1. NM_180865.1.
UniGeneiAt.20254.

3D structure databases

ProteinModelPortaliQ8LBL1.
SMRiQ8LBL1.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi20901. 27 interactors.
STRINGi3702.AT5G55630.1.

Protein family/group databases

TCDBi1.A.1.7.3. the voltage-gated ion channel (vic) superfamily.

PTM databases

iPTMnetiQ8LBL1.

Proteomic databases

PaxDbiQ8LBL1.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsemblPlantsiAT5G55630.1; AT5G55630.1; AT5G55630.
AT5G55630.2; AT5G55630.2; AT5G55630.
GeneIDi835657.
GrameneiAT5G55630.1; AT5G55630.1; AT5G55630.
AT5G55630.2; AT5G55630.2; AT5G55630.
KEGGiath:AT5G55630.

Organism-specific databases

TAIRiAT5G55630.

Phylogenomic databases

eggNOGiKOG1418. Eukaryota.
COG1226. LUCA.
HOGENOMiHOG000238193.
InParanoidiQ8LBL1.
KOiK05389.
OrthoDBiEOG09360EZI.
PhylomeDBiQ8LBL1.

Enzyme and pathway databases

BioCyciARA:AT5G55630-MONOMER.
MetaCyc:MONOMER-14554.

Miscellaneous databases

PROiQ8LBL1.

Gene expression databases

GenevisibleiQ8LBL1. AT.

Family and domain databases

Gene3Di1.10.238.10. 1 hit.
InterProiIPR003280. 2pore_dom_K_chnl.
IPR011992. EF-hand-dom_pair.
IPR018247. EF_Hand_1_Ca_BS.
IPR013099. K_chnl_dom.
IPR031144. TPK_plant.
[Graphical view]
PANTHERiPTHR11003:SF135. PTHR11003:SF135. 1 hit.
PfamiPF07885. Ion_trans_2. 2 hits.
[Graphical view]
PRINTSiPR01333. 2POREKCHANEL.
SUPFAMiSSF47473. SSF47473. 1 hit.
PROSITEiPS00018. EF_HAND_1. 2 hits.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiKCO1_ARATH
AccessioniPrimary (citable) accession number: Q8LBL1
Secondary accession number(s): O04718, Q0WNY4, Q9FM75
Entry historyi
Integrated into UniProtKB/Swiss-Prot: November 28, 2003
Last sequence update: November 28, 2003
Last modified: November 2, 2016
This is version 126 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Miscellaneousi

Miscellaneous

14-3-3 protein binding is not involved in endoplasmic reticulum export and tonoplast targeting.

Caution

Was initially described as an outward slow-vacuolar (SV) ion channel (PubMed:9184204 and PubMed:11821043).Curated

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. Arabidopsis thaliana
    Arabidopsis thaliana: entries and gene names
  2. SIMILARITY comments
    Index of protein domains and families

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.