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Protein

Calcium-activated potassium channel subunit alpha-1

Gene

KCNMA1

Organism
Sus scrofa (Pig)
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 similarity

Enzyme regulationi

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

Sites

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Metal bindingi413 – 4131MagnesiumBy similarity
Metal bindingi436 – 4361MagnesiumBy similarity
Metal bindingi438 – 4381MagnesiumBy similarity
Metal bindingi928 – 9281Calcium; via carbonyl oxygenBy similarity
Metal bindingi931 – 9311Calcium; via carbonyl oxygenBy similarity
Metal bindingi934 – 9341CalciumBy similarity
Metal bindingi936 – 9361CalciumBy similarity

GO - Molecular functioni

GO - Biological processi

  • positive regulation of membrane hyperpolarization Source: AgBase
  • relaxation of vascular smooth muscle Source: AgBase
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
OrganismiSus scrofa (Pig)
Taxonomic identifieri9823 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaLaurasiatheriaCetartiodactylaSuinaSuidaeSus
Proteomesi
  • UP000008227 Componenti: Unplaced

Subcellular locationi

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini‹1 – 60›60ExtracellularSequence analysisAdd
BLAST
Transmembranei61 – 8121Helical; Name=Segment S0Sequence analysisAdd
BLAST
Topological domaini82 – 15271CytoplasmicSequence analysisAdd
BLAST
Transmembranei153 – 17321Helical; Name=Segment S1Sequence analysisAdd
BLAST
Topological domaini174 – 18815ExtracellularSequence analysisAdd
BLAST
Transmembranei189 – 20921Helical; Name=Segment S2Sequence analysisAdd
BLAST
Topological domaini210 – 2134CytoplasmicSequence analysis
Transmembranei214 – 23421Helical; Name=Segment S3Sequence analysisAdd
BLAST
Topological domaini235 – 2384ExtracellularSequence analysis
Transmembranei239 – 25921Helical; Voltage-sensor; Name=Segment S4Sequence analysisAdd
BLAST
Topological domaini260 – 27415CytoplasmicSequence analysisAdd
BLAST
Transmembranei275 – 29521Helical; Name=Segment S5Sequence analysisAdd
BLAST
Topological domaini296 – 30914ExtracellularSequence analysisAdd
BLAST
Intramembranei310 – 33223Pore-forming; Name=P regionSequence analysisAdd
BLAST
Topological domaini333 – 3419ExtracellularSequence analysis
Transmembranei342 – 36221Helical; Name=Segment S6Sequence analysisAdd
BLAST
Topological domaini363 – 1152790CytoplasmicSequence analysisAdd
BLAST

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Membrane

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini‹1 – 1152›1152Calcium-activated potassium channel subunit alpha-1PRO_0000054135Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Lipidationi92 – 921S-palmitoyl cysteineBy similarity
Lipidationi93 – 931S-palmitoyl cysteineBy similarity
Lipidationi95 – 951S-palmitoyl cysteineBy similarity
Modified residuei679 – 6791PhosphothreonineBy similarity
Modified residuei681 – 6811PhosphoserineBy similarity
Modified residuei694 – 6941PhosphoserineBy similarity
Modified residuei698 – 6981PhosphoserineBy similarity
Modified residuei886 – 8861PhosphothreonineBy similarity
Modified residuei894 – 8941PhosphoserineBy similarity
Modified residuei898 – 8981PhosphoserineBy similarity

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

PaxDbiO18866.

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

Protein-protein interaction databases

STRINGi9823.ENSSSCP00000011011.

Structurei

3D structure databases

ProteinModelPortaliO18866.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini389 – 532144RCK N-terminalAdd
BLAST

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni530 – 55021Segment S7Add
BLAST
Regioni587 – 60721Segment S8Add
BLAST
Regioni651 – 6555Heme-binding motif
Regioni753 – 77321Segment S9Add
BLAST
Regioni948 – 96821Segment S10Add
BLAST

Motif

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Motifi326 – 3294Selectivity for potassiumBy similarity
Motifi919 – 94123Calcium bowlAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi15 – 3420Poly-SerAdd
BLAST

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.
InParanoidiO18866.
KOiK04936.

Family and domain databases

Gene3Di3.40.50.720. 1 hit.
InterProiIPR005821. Ion_trans_dom.
IPR003929. K_chnl_Ca-activ_BK_asu.
IPR016040. NAD(P)-bd_dom.
IPR028325. VG_K_chnl.
[Graphical view]
PfamiPF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
[Graphical view]
PRINTSiPR01449. BKCHANNELA.
PR00169. KCHANNEL.
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: O18866-1) [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
MSSNIHANHL SLDASSSSSS SSSSSSSSSS SSSSVHEPKM DALIIPVTME
60 70 80 90 100
VPCDSRGQRM WWAFLASSMV TFFGGLFIIL LWRTLKYLWT VCCHCGGKTK
110 120 130 140 150
EAQKINNGAS QADGTLKPVD EKEEVVAAEV GWMTSVKDWA GVMISAQTLT
160 170 180 190 200
GRVLVVLVFA LSIGALVIYF IDSSNPIESC QNFYKDFTLQ IDMAFNVFFL
210 220 230 240 250
LYFGLRFIAA NDKLWFWLEV NSVVDFFTVP PVFVSVYLNR SWLGLRFLRA
260 270 280 290 300
LRLIQFSEIL QFLNILKTSN SIKLVNLLSI FISTWLTAAG FIHLVENSGD
310 320 330 340 350
PWENFQNNQA LTYWECVYLL MVTMSTVGYG DVYAKTTLGR LFMVFFILGG
360 370 380 390 400
LAMFASYVPE IIELIGNRKK YGGSYSAVSG RKHIVVCGHI TLESVSNFLK
410 420 430 440 450
DFLHKDRDDV NVEIVFLHNI SPNLELEALF KRHFTQVEFY QGSVLNPHDL
460 470 480 490 500
ARVKIESADA CLILANKYCA DPDAEDASNI MRVISIKNYH PKIRIITQML
510 520 530 540 550
QYHNKAHLLN IPSWNWKEGD DAICLAELKL GFIAQSCLAQ GLSTMLANLF
560 570 580 590 600
SMRSFIKIEE DTWQKYYLEG VSNEMYTEYL SSAFVGLSFP TVCELCFVKL
610 620 630 640 650
KLLMIAIEYK SANRESRILI NPGNHLKIQE GTLGFFIASD AKEVKRAFFY
660 670 680 690 700
CKACHDDITD PKRIKKCGCK RLEDEQPSTL SPKKKQRNGG MRNSPSSSPK
710 720 730 740 750
LMRHDPLLIP GNDQIDNMDS NVKKYDSTGM FHWCAPKEIE KVILTRSEAA
760 770 780 790 800
MTVLSGHVVV CIFGDVSSAL IGLRNLVMPL RASNFHYHEL KHIVFVGSIE
810 820 830 840 850
YLKREWETLH NFPKVSILPG TPLSRADLRA VNINLCDMCV ILSANQNNID
860 870 880 890 900
DTSLQDKECI LASLNIKSMQ FDDSIGVLQA NSQGFTPPGM DRSSPDNSPV
910 920 930 940 950
HGMLRQPSIT TGVNIPIITE LVNDTNVQFL DQDDDDDPDT ELYLTQPFAC
960 970 980 990 1000
GTAFAVSVLD SLMSATYFND NILTLIRTLV TGGATPELEA LIAEENALRG
1010 1020 1030 1040 1050
GYSTPQTLAN RDRCRVAQLA LLDGPFADLG DGGCYGDLFC KALKTYNMLC
1060 1070 1080 1090 1100
FGIYRLRDAH LSTPSQCTKR YVITNPPYEF ELVPTDLIFC LMQFDHNAGQ
1110 1120 1130 1140 1150
SRASLSHSSH SSQSSSKKSS SVHSIPSTAN RQNRPKSRES RDKQKYVQEE

RL
Length:1,152
Mass (Da):129,006
Last modified:March 1, 2004 - v2
Checksum:iF656770B0C031806
GO

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Non-terminal residuei1 – 11

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF026000 mRNA. Translation: AAB88803.2.
RefSeqiNP_999384.1. NM_214219.1. [O18866-1]
UniGeneiSsc.16143.

Genome annotation databases

GeneIDi397434.
KEGGissc:397434.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF026000 mRNA. Translation: AAB88803.2.
RefSeqiNP_999384.1. NM_214219.1. [O18866-1]
UniGeneiSsc.16143.

3D structure databases

ProteinModelPortaliO18866.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

STRINGi9823.ENSSSCP00000011011.

Proteomic databases

PaxDbiO18866.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi397434.
KEGGissc:397434.

Organism-specific databases

CTDi3778.

Phylogenomic databases

eggNOGiKOG1420. Eukaryota.
ENOG410YUX1. LUCA.
HOGENOMiHOG000019856.
HOVERGENiHBG052222.
InParanoidiO18866.
KOiK04936.

Family and domain databases

Gene3Di3.40.50.720. 1 hit.
InterProiIPR005821. Ion_trans_dom.
IPR003929. K_chnl_Ca-activ_BK_asu.
IPR016040. NAD(P)-bd_dom.
IPR028325. VG_K_chnl.
[Graphical view]
PfamiPF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
[Graphical view]
PRINTSiPR01449. BKCHANNELA.
PR00169. KCHANNEL.
SUPFAMiSSF51735. SSF51735. 1 hit.
ProtoNetiSearch...

Publicationsi

  1. "Ion transporters and receptors in cDNA libraries from lens and cornea epithelia."
    Shepard A.R., Rae J.L.
    Curr. Eye Res. 17:708-719(1998) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA].
    Tissue: Lens epithelium.

Entry informationi

Entry nameiKCMA1_PIG
AccessioniPrimary (citable) accession number: O18866
Entry historyi
Integrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: March 1, 2004
Last modified: February 17, 2016
This is version 112 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.