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Protein

Two-pore potassium channel 1

Gene

TPK1

Organism
Arabidopsis thaliana (Mouse-ear cress)
Status
Reviewed-Annotation score: -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

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

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
  • potassium ion leak channel activity Source: GO_Central

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
  • stabilization of membrane potential Source: GO_Central

Keywordsi

Molecular functionIon channel, Potassium channel
Biological processIon transport, Potassium transport, Transport
LigandCalcium, 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

AraportiAT5G55630
TAIRilocus:2162162 AT5G55630

Subcellular locationi

Extracellular region or secreted Cytosol Plasma membrane Cell wall Cytoskeleton Vacuole Chloroplast Endosome Peroxisome ER Golgi apparatus Nucleus Mitochondrion Manual annotation Automatic computational assertion Graphics by Christian Stolte; Source: COMPARTMENTS

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

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

ExpressionAtlasiQ8LBL1 baseline and differential
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
IntActiQ8LBL1, 2 interactors
STRINGi3702.AT5G55630.1

Structurei

3D structure databases

ProteinModelPortaliQ8LBL1
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

Keywords - Domaini

Repeat, Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG1418 Eukaryota
COG1226 LUCA
HOGENOMiHOG000238193
InParanoidiQ8LBL1
KOiK05389
OMAiHPSKIPM
OrthoDBiEOG09360EZI
PhylomeDBiQ8LBL1

Family and domain databases

InterProiView protein in InterPro
IPR003280 2pore_dom_K_chnl
IPR011992 EF-hand-dom_pair
IPR018247 EF_Hand_1_Ca_BS
IPR013099 K_chnl_dom
PfamiView protein in Pfam
PF07885 Ion_trans_2, 2 hits
PRINTSiPR01333 2POREKCHANEL
SUPFAMiSSF47473 SSF47473, 1 hit
PROSITEiView protein in PROSITE
PS00018 EF_HAND_1, 2 hits

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

Similar proteinsi

Entry informationi

Entry nameiKCO1_ARATH
AccessioniPrimary (citable) accession number: Q8LBL1
Secondary accession number(s): O04718, Q0WNY4, Q9FM75
Entry historyiIntegrated into UniProtKB/Swiss-Prot: November 28, 2003
Last sequence update: November 28, 2003
Last modified: May 23, 2018
This is version 137 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programPlant Protein Annotation Program

Miscellaneousi

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

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