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Protein

Calcium-activated potassium channel subunit alpha-1

Gene

KCNMA1

Organism
Macaca mulatta (Rhesus macaque)
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 bindingi412 – 4121MagnesiumBy similarity
Metal bindingi435 – 4351MagnesiumBy similarity
Metal bindingi437 – 4371MagnesiumBy similarity
Metal bindingi927 – 9271Calcium; via carbonyl oxygenBy similarity
Metal bindingi930 – 9301Calcium; via carbonyl oxygenBy similarity
Metal bindingi933 – 9331CalciumBy similarity
Metal bindingi935 – 9351CalciumBy similarity

GO - Molecular functioni

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
OrganismiMacaca mulatta (Rhesus macaque)
Taxonomic identifieri9544 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniCercopithecidaeCercopithecinaeMacaca
Proteomesi
  • UP000006718 Componenti: Unplaced

Subcellular locationi

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini‹1 – 59›59ExtracellularSequence analysisAdd
BLAST
Transmembranei60 – 8021Helical; Name=Segment S0Sequence analysisAdd
BLAST
Topological domaini81 – 15171CytoplasmicSequence analysisAdd
BLAST
Transmembranei152 – 17221Helical; Name=Segment S1Sequence analysisAdd
BLAST
Topological domaini173 – 18715ExtracellularSequence analysisAdd
BLAST
Transmembranei188 – 20821Helical; Name=Segment S2Sequence analysisAdd
BLAST
Topological domaini209 – 2124CytoplasmicSequence analysis
Transmembranei213 – 23321Helical; Name=Segment S3Sequence analysisAdd
BLAST
Topological domaini234 – 2374ExtracellularSequence analysis
Transmembranei238 – 25821Helical; Voltage-sensor; Name=Segment S4Sequence analysisAdd
BLAST
Topological domaini259 – 27315CytoplasmicSequence analysisAdd
BLAST
Transmembranei274 – 29421Helical; Name=Segment S5Sequence analysisAdd
BLAST
Topological domaini295 – 30814ExtracellularSequence analysisAdd
BLAST
Intramembranei309 – 33123Pore-forming; Name=P regionSequence analysisAdd
BLAST
Topological domaini332 – 3409ExtracellularSequence analysis
Transmembranei341 – 36121Helical; Name=Segment S6Sequence analysisAdd
BLAST
Topological domaini362 – 1151790CytoplasmicSequence 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 – 1151›1151Calcium-activated potassium channel subunit alpha-1PRO_0000054133Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Lipidationi91 – 911S-palmitoyl cysteineBy similarity
Lipidationi92 – 921S-palmitoyl cysteineBy similarity
Lipidationi94 – 941S-palmitoyl cysteineBy similarity
Modified residuei678 – 6781PhosphothreonineBy similarity
Modified residuei680 – 6801PhosphoserineBy similarity
Modified residuei693 – 6931PhosphoserineBy similarity
Modified residuei697 – 6971PhosphoserineBy similarity
Modified residuei885 – 8851PhosphothreonineBy similarity
Modified residuei893 – 8931PhosphoserineBy similarity
Modified residuei897 – 8971PhosphoserineBy 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

Expressioni

Gene expression databases

BgeeiENSMMUG00000018390.

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

Structurei

3D structure databases

ProteinModelPortaliO18867.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini388 – 531144RCK N-terminalAdd
BLAST

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni529 – 54921Segment S7Add
BLAST
Regioni586 – 60621Segment S8Add
BLAST
Regioni650 – 6545Heme-binding motif
Regioni752 – 77221Segment S9Add
BLAST
Regioni947 – 96721Segment S10Add
BLAST

Motif

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Motifi325 – 3284Selectivity for potassium
Motifi918 – 94023Calcium bowlAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi15 – 3319Poly-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

HOGENOMiHOG000019856.
HOVERGENiHBG052222.
InParanoidiO18867.
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: O18867-1) [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 SSSVHEPKMD ALIIPVTMEV
60 70 80 90 100
PCDSRGQRMW WAFLASSMVT FFGGLFIILL WRTLKYLWTV CCHCGGKTKE
110 120 130 140 150
AQKINNGSSQ ADGTLKPVDE KEEAVAAEVG WMTSVKDWAG VMISAQTLTG
160 170 180 190 200
RVLVVLVFAL SIGALVIYFI DSSNPIESCQ NFYKDFTLQI DMAFNVFFLL
210 220 230 240 250
YFGLRFIAAN DKLWFWLEVN SVVDFFTVPP VFVSVYLNRS WLGLRFLRAL
260 270 280 290 300
RLIQFSEILQ FLNILKTSNS IKLVNLLSIF ISTWLTAAGF IHLVENSGDP
310 320 330 340 350
WENFQNNQAL TYWECVYLLM VTMSTVGYGD VYAKTTLGRL FMVFFILGGL
360 370 380 390 400
AMFASYVPEI IELIGNRKKY GGSYSAVSGR KHIVVCGHIT LESVSNFLKD
410 420 430 440 450
FLHKDRDDVN VEIVFLHNIS PNLELEALFK RHFTQVEFYQ GSVLNPHDLA
460 470 480 490 500
RVKIESADAC LILANKYCAD PDAEDASNIM RVISIKNYHP KIRIITQMLQ
510 520 530 540 550
YHNKAHLLNI PSWNWKEGDD AICLAELKLG FIAQSCLAQG LSTMLANLFS
560 570 580 590 600
MRSFIKIEED TWQKYYLEGV SNEMYTEYLS SAFVGLSFPT VCELCFVKLK
610 620 630 640 650
LLMIAIEYKS ANRESRILIN PGNHLKIQEG TLGFFIASDA KEVKRAFFYC
660 670 680 690 700
KACHDDITDP KRIKKCGCKR LEDEQPSTLS PKKKQRNGGM RNSPNSSPKL
710 720 730 740 750
MRHDPLLIPG NDQIDNMDSN VKKYDSTGMF HWCAPKEIEK VILTRSEAAM
760 770 780 790 800
TVLSGHVVVC IFGDVSSALI GLRNLVMPLR ASNFHYHELK HIVFVGSIEY
810 820 830 840 850
LKREWETLHN FPKVSILPGT PLSRADLRAV NINLCDMCVI LSANQNNIDD
860 870 880 890 900
TSLQDKECIL ASLNIKSMQF DDSIGVLQAN SQGFTPPGMD RSSPDNSPVH
910 920 930 940 950
GMLRQPSITT GVNIPIITEL VNDTNVQFLD QDDDDDPDTE LYLTQPFACG
960 970 980 990 1000
TAFAVSVLDS LMSATYFNDN ILTLIRTLVT GGATPELEAL IAEENALRGG
1010 1020 1030 1040 1050
YSTPQTLANR DRCRVAQLAL LDGPFADLGD GGCYGDLFCK ALKTYNMLCF
1060 1070 1080 1090 1100
GIYRLRDAHL STPSQCTKRY VITNPPYEFE LVPTDLIFCL MQFDHNAGQS
1110 1120 1130 1140 1150
RASLSHSSHS SQSSSKKSSS VHSIPSTANR QNRPKSRESR DKQKYVQEER

L
Length:1,151
Mass (Da):128,934
Last modified:January 1, 1998 - v1
Checksum:i24E62FE0C1D94015
GO

Experimental Info

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

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF026001 mRNA. Translation: AAB88804.1.
RefSeqiNP_001027982.1. NM_001032810.1. [O18867-1]
UniGeneiMmu.22715.
Mmu.3423.

Genome annotation databases

GeneIDi574103.
KEGGimcc:574103.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF026001 mRNA. Translation: AAB88804.1.
RefSeqiNP_001027982.1. NM_001032810.1. [O18867-1]
UniGeneiMmu.22715.
Mmu.3423.

3D structure databases

ProteinModelPortaliO18867.
ModBaseiSearch...
MobiDBiSearch...

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi574103.
KEGGimcc:574103.

Organism-specific databases

CTDi3778.

Phylogenomic databases

HOGENOMiHOG000019856.
HOVERGENiHBG052222.
InParanoidiO18867.
KOiK04936.

Gene expression databases

BgeeiENSMMUG00000018390.

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...

Entry informationi

Entry nameiKCMA1_MACMU
AccessioniPrimary (citable) accession number: O18867
Entry historyi
Integrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: January 1, 1998
Last modified: September 7, 2016
This is version 113 of the entry and version 1 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.