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Protein

Calcium-activated potassium channel subunit alpha-1

Gene

KCNMA1

Organism
Canis lupus familiaris (Dog) (Canis familiaris)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at transcript leveli

Functioni

Potassium channel activated by both membrane depolarization or increase in cytosolic Ca2+ that mediates export of K+. It is also activated by the concentration of cytosolic Mg2+. Its activation dampens the excitatory events that elevate the cytosolic Ca2+ concentration and/or depolarize the cell membrane. It therefore contributes to repolarization of the membrane potential. Plays a key role in controlling excitability in a number of systems, such as regulation of the contraction of smooth muscle, the tuning of hair cells in the cochlea, regulation of transmitter release, and innate immunity. In smooth muscles, its activation by high level of Ca2+, caused by ryanodine receptors in the sarcoplasmic reticulum, regulates the membrane potential. In cochlea cells, its number and kinetic properties partly determine the characteristic frequency of each hair cell and thereby helps to establish a tonotopic map. Kinetics of KCNMA1 channels are determined by alternative splicing, phosphorylation status and its combination with modulating beta subunits. Highly sensitive to both iberiotoxin (IbTx) and charybdotoxin (CTX) (By similarity).By similarity1 Publication

Enzyme regulationi

Ethanol and carbon monoxide-bound heme increase channel activation. Heme inhibits channel activation (By similarity).By similarity

Sites

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Metal bindingi377MagnesiumBy similarity1
Metal bindingi400MagnesiumBy similarity1
Metal bindingi402MagnesiumBy similarity1
Metal bindingi892Calcium; via carbonyl oxygenBy similarity1
Metal bindingi895Calcium; via carbonyl oxygenBy similarity1
Metal bindingi898CalciumBy similarity1
Metal bindingi900CalciumBy similarity1

GO - Molecular functioni

GO - Biological processi

Complete GO annotation...

Keywords - Molecular functioni

Ion channel, Potassium channel, Voltage-gated channel

Keywords - Biological processi

Ion transport, Potassium transport, Transport

Keywords - Ligandi

Calcium, Magnesium, Metal-binding, Potassium

Names & Taxonomyi

Protein namesi
Recommended name:
Calcium-activated potassium channel subunit alpha-1
Alternative name(s):
BK channel
BKCA alpha
Calcium-activated potassium channel, subfamily M subunit alpha-1
K(VCA)alpha
KCa1.1
Maxi K channel
Short name:
MaxiK
Slo-alpha
Slo1
Slowpoke homolog
Short name:
Slo homolog
Gene namesi
Name:KCNMA1
Synonyms:KCNMA
OrganismiCanis lupus familiaris (Dog) (Canis familiaris)
Taxonomic identifieri9615 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaLaurasiatheriaCarnivoraCaniformiaCanidaeCanis
Proteomesi
  • UP000002254 Componenti: Unplaced

Subcellular locationi

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Topological domaini‹1 – 24ExtracellularSequence analysisAdd BLAST›24
Transmembranei25 – 45Helical; Name=Segment S0Sequence analysisAdd BLAST21
Topological domaini46 – 116CytoplasmicSequence analysisAdd BLAST71
Transmembranei117 – 137Helical; Name=Segment S1Sequence analysisAdd BLAST21
Topological domaini138 – 152ExtracellularSequence analysisAdd BLAST15
Transmembranei153 – 173Helical; Name=Segment S2Sequence analysisAdd BLAST21
Topological domaini174 – 177CytoplasmicSequence analysis4
Transmembranei178 – 198Helical; Name=Segment S3Sequence analysisAdd BLAST21
Topological domaini199 – 202ExtracellularSequence analysis4
Transmembranei203 – 223Helical; Voltage-sensor; Name=Segment S4Sequence analysisAdd BLAST21
Topological domaini224 – 238CytoplasmicSequence analysisAdd BLAST15
Transmembranei239 – 259Helical; Name=Segment S5Sequence analysisAdd BLAST21
Topological domaini260 – 273ExtracellularSequence analysisAdd BLAST14
Intramembranei274 – 296Pore-forming; Name=P regionSequence analysisAdd BLAST23
Topological domaini297 – 305ExtracellularSequence analysis9
Transmembranei306 – 326Helical; Name=Segment S6Sequence analysisAdd BLAST21
Topological domaini327 – 1159CytoplasmicSequence analysisAdd BLAST833

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_0000054131‹1 – 1159Calcium-activated potassium channel subunit alpha-1Add BLAST›1159

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Lipidationi56S-palmitoyl cysteineBy similarity1
Lipidationi57S-palmitoyl cysteineBy similarity1
Lipidationi59S-palmitoyl cysteineBy similarity1
Modified residuei643PhosphothreonineBy similarity1
Modified residuei645PhosphoserineBy similarity1
Modified residuei658PhosphoserineBy similarity1
Modified residuei662PhosphoserineBy similarity1
Modified residuei850PhosphothreonineBy similarity1
Modified residuei858PhosphoserineBy similarity1
Modified residuei862PhosphoserineBy similarity1

Post-translational modificationi

Phosphorylated (Probable). Phosphorylation by kinases such as PKA and/or PKG. In smooth muscles, phosphorylation affects its activity (By similarity).By similarityCurated
Palmitoylation by ZDHHC22 and ZDHHC23 within the intracellular linker between the S0 and S1 transmembrane domains regulates localization to the plasma membrane. Depalmitoylated by LYPLA1 and LYPLAL1, leading to retard exit from the trans-Golgi network (By similarity).By similarity

Keywords - PTMi

Lipoprotein, Palmitate, Phosphoprotein

Proteomic databases

PaxDbiQ28265.

PTM databases

iPTMnetiQ28265.

Expressioni

Tissue specificityi

Expressed in all vascular and smooth muscles.1 Publication

Interactioni

Subunit structurei

Homotetramer; which constitutes the calcium-activated potassium channel. Interacts with beta subunits KCNMB1, KCNMB2, KCNMB3 and KCNMB4. Interacts with gamma subunits LRRC26, LRRC38, LRRC52 and LRRC55. Beta and gamma subunits are accessory, and modulate its activity. Interacts with RAB11B (By similarity).By similarity

GO - Molecular functioni

Protein-protein interaction databases

STRINGi9615.ENSCAFP00000022780.

Structurei

3D structure databases

ProteinModelPortaliQ28265.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini353 – 496RCK N-terminalAdd BLAST144

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni494 – 514Segment S7Add BLAST21
Regioni551 – 571Segment S8Add BLAST21
Regioni615 – 619Heme-binding motif5
Regioni717 – 737Segment S9Add BLAST21
Regioni912 – 932Segment S10Add BLAST21

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi290 – 293Selectivity for potassium4
Motifi883 – 905Calcium bowlAdd BLAST23

Domaini

The S0 segment is essential for the modulation by the accessory beta subunits KCNMB1, KCNMB2, KCNMB3 and KCNMB4.By similarity
The S4 segment, which is characterized by a series of positively charged amino acids at every third position, is part of the voltage-sensor.By similarity
The pore-forming domain (also referred as P region) is imbedded into the membrane, and forms the selectivity filter of the pore. It contains the signature sequence of potassium channels that displays selectivity to potassium (By similarity).By similarity
The RCK N-terminal domain mediates the homotetramerization, thereby promoting the assembly of monomers into functional potassium channel. It includes binding sites for Ca2+ and Mg2+ (By similarity).By similarity
The calcium bowl constitutes one of the Ca2+ sensors and probably acts as a Ca2+-binding site. There are however other Ca2+ sensors regions required for activation of the channel (By similarity).By similarity
The heme-binding motif mediates inhibition of channel activation by heme. Carbon monoxide-bound heme leads to increased channel activation (By similarity).By similarity

Sequence similaritiesi

Contains 1 RCK N-terminal domain.Curated

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG1420. Eukaryota.
ENOG410YUX1. LUCA.
HOGENOMiHOG000019856.
HOVERGENiHBG052222.
InParanoidiQ28265.
KOiK04936.

Family and domain databases

Gene3Di3.40.50.720. 2 hits.
InterProiIPR005821. Ion_trans_dom.
IPR003929. K_chnl_Ca-activ_BK_asu.
IPR016040. NAD(P)-bd_dom.
[Graphical view]
PfamiPF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
[Graphical view]
PRINTSiPR01449. BKCHANNELA.
SUPFAMiSSF51735. SSF51735. 1 hit.

Sequencei

Sequence statusi: Fragment.

This entry describes 1 isoform i produced by alternative splicing. AlignAdd to basket

Note: May be partially controlled by hormonal stress. A number of isoforms are produced.
Isoform 1 (identifier: Q28265-1) [UniParc]FASTAAdd to basket

This isoform has been chosen as the 'canonical' sequence. All positional information in this entry refers to it. This is also the sequence that appears in the downloadable versions of the entry.

« Hide

        10         20         30         40         50
EPNMDALIIP VTMEVPCDSR GQRMWWAFLA SSMVTFFGGL FIILLWRTLK
60 70 80 90 100
YLWTVCCHCG DKTKEAQKIN NGSSQADGTL KPVDEKEEAV AAEVGWMTSV
110 120 130 140 150
KDWAGVMISA QTLTGRVLVV LVFALSIGAL VIYFIDSSNP IESCQNFYKD
160 170 180 190 200
FTLQIDMAFN VFFLLYFGLR FIAANDNLWF WLEVNSVVDF FTVPPVFVSV
210 220 230 240 250
YLNRSWLGLR FLRALRLIQF SEILQFLNIL KTSNSIKLVN LLSIFISTWL
260 270 280 290 300
TAAGFIHLVE NSGDPWENFQ NSQALTYWEC VYLLMVTMST VGYGDVYAKT
310 320 330 340 350
TPGGLFIVFF ILGGLAMFAS YVPEIIEIIG NRKKYGGSYS AVSGRKHIVV
360 370 380 390 400
CGHITLESVS HFLKDFLHKD RDDVNVEIVF LHNISPNLEL EALFKRHFTQ
410 420 430 440 450
VEFYQGSVLN PHDLARVKIE SADACLILAN KYCDDPDAED ASNIMRVISI
460 470 480 490 500
KNYHPKIRII TQMLQYHNKA HLLNIPSWNW KEGDDAICLA ELRLGFIAQS
510 520 530 540 550
CLAQGLSTML ANLFSIGSFI KIEEDTWHKY YLEGVSNEMY TEYLSSAFVG
560 570 580 590 600
LSFPTVCELC FVKLKLLMIA IEYKSANRES RILINPGNHL KIQEGTSGFF
610 620 630 640 650
IASDAKEVKR AFFYCKACHN DITDPKRIKK CGCKRLEDEQ PSTLSPKKKQ
660 670 680 690 700
RNGGMRNSPS SSPKLMRHDP LLIPGNDQID NMDSNVKKYD STGMFHWCAP
710 720 730 740 750
KEIEKVISTR SEAAMTVLSG HVVVCIFGHV SSALIGLRNL VMPLRASNFH
760 770 780 790 800
YHELKHIVFV GSIEYLKREW ETLHNFPKVS ILPGTPLTRA DLRAVNINLC
810 820 830 840 850
DMCVILSANQ NNIDDTSLQD KECILASLNI KSMQFDDSIG VLQANSQGFT
860 870 880 890 900
PPGMDKSSPD NSPVHGMLRQ PSITTGVNIP IITELVNDTN VQFLDQDDDD
910 920 930 940 950
DPDTELYLTQ PFACGTAFAV SVLDSLMSAT YFNDNILTLI RTLVTGGATP
960 970 980 990 1000
ELEALIAEEN ALRGGYSTPQ TLANRDRCRV AQLALLDGPF ADLGDGGCYG
1010 1020 1030 1040 1050
DLFCKALKTY NMLCFGIYRL RDAHLSTPSQ CTKRYVITNP PYRFELVPTD
1060 1070 1080 1090 1100
LIFCLMQFDH NAGQSRASLS HSSHSSQSSS KKSSSVHSIP STANRQNRPK
1110 1120 1130 1140 1150
SRESRDKQTE KKWFTDEPDN AYPRNIQIEP MSTHMANQIN QYKSTSSLIP

PIREVEDEC
Length:1,159
Mass (Da):130,296
Last modified:April 13, 2004 - v2
Checksum:iD8CF38C32971BB64
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Non-terminal residuei11

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U41001 mRNA. Translation: AAA84000.1.
RefSeqiNP_001003300.2. NM_001003300.2.
UniGeneiCfa.21938.
Cfa.3853.

Genome annotation databases

GeneIDi403984.
KEGGicfa:403984.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U41001 mRNA. Translation: AAA84000.1.
RefSeqiNP_001003300.2. NM_001003300.2.
UniGeneiCfa.21938.
Cfa.3853.

3D structure databases

ProteinModelPortaliQ28265.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

STRINGi9615.ENSCAFP00000022780.

PTM databases

iPTMnetiQ28265.

Proteomic databases

PaxDbiQ28265.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi403984.
KEGGicfa:403984.

Organism-specific databases

CTDi3778.

Phylogenomic databases

eggNOGiKOG1420. Eukaryota.
ENOG410YUX1. LUCA.
HOGENOMiHOG000019856.
HOVERGENiHBG052222.
InParanoidiQ28265.
KOiK04936.

Family and domain databases

Gene3Di3.40.50.720. 2 hits.
InterProiIPR005821. Ion_trans_dom.
IPR003929. K_chnl_Ca-activ_BK_asu.
IPR016040. NAD(P)-bd_dom.
[Graphical view]
PfamiPF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
[Graphical view]
PRINTSiPR01449. BKCHANNELA.
SUPFAMiSSF51735. SSF51735. 1 hit.
ProtoNetiSearch...

Entry informationi

Entry nameiKCMA1_CANLF
AccessioniPrimary (citable) accession number: Q28265
Entry historyi
Integrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: April 13, 2004
Last modified: November 30, 2016
This is version 124 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Miscellaneous

The protein was initially thought to contain two functionally distinct parts: The core channel (from the N-terminus to the S9 segment) that mediates the channel activity, and the cytoplasmic tail (from the S9 segment to the C-terminus) that mediates the calcium sensing. The situation is however more complex, since the core channel contains binding sites for Ca2+ and Mg2+.

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. 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.