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Protein

Calcium-activated potassium channel subunit alpha-1

Gene

KCNMA1

Organism
Gallus gallus (Chicken)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein 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. Highly sensitive to both iberiotoxin (IbTx) and charybdotoxin (CTX).1 Publication

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+.

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 bindingi398MagnesiumBy similarity1
Metal bindingi421MagnesiumBy similarity1
Metal bindingi423MagnesiumBy similarity1
Metal bindingi913Calcium; via carbonyl oxygenBy similarity1
Metal bindingi916Calcium; via carbonyl oxygenBy similarity1
Metal bindingi919CalciumBy similarity1
Metal bindingi921CalciumBy similarity1

GO - Molecular functioni

Keywordsi

Molecular functionIon channel, Potassium channel, Voltage-gated channel
Biological processIon transport, Potassium transport, Transport
LigandCalcium, Magnesium, Metal-binding, Potassium

Enzyme and pathway databases

ReactomeiR-GGA-1296052. Ca2+ activated K+ channels.

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
Short name:
cSlo
Gene namesi
Name:KCNMA1
Synonyms:KCNMA
OrganismiGallus gallus (Chicken)
Taxonomic identifieri9031 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiArchelosauriaArchosauriaDinosauriaSaurischiaTheropodaCoelurosauriaAvesNeognathaeGalloanseraeGalliformesPhasianidaePhasianinaeGallus
Proteomesi
  • UP000000539 Componenti: Chromosome 6

Subcellular locationi

Extracellular region or secreted Cytosol Plasma membrane Cytoskeleton Lysosome Endosome Peroxisome ER Golgi apparatus Nucleus Mitochondrion Manual annotation Automatic computational assertionGraphics by Christian Stolte; Source: COMPARTMENTS

Topology

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Topological domaini1 – 44ExtracellularSequence analysisAdd BLAST44
Transmembranei45 – 65Helical; Name=Segment S0Sequence analysisAdd BLAST21
Topological domaini66 – 137CytoplasmicSequence analysisAdd BLAST72
Transmembranei138 – 158Helical; Name=Segment S1Sequence analysisAdd BLAST21
Topological domaini159 – 173ExtracellularSequence analysisAdd BLAST15
Transmembranei174 – 194Helical; Name=Segment S2Sequence analysisAdd BLAST21
Topological domaini195 – 198CytoplasmicSequence analysis4
Transmembranei199 – 219Helical; Name=Segment S3Sequence analysisAdd BLAST21
Topological domaini220 – 223ExtracellularSequence analysis4
Transmembranei224 – 244Helical; Voltage-sensor; Name=Segment S4Sequence analysisAdd BLAST21
Topological domaini245 – 259CytoplasmicSequence analysisAdd BLAST15
Transmembranei260 – 280Helical; Name=Segment S5Sequence analysisAdd BLAST21
Topological domaini281 – 294ExtracellularSequence analysisAdd BLAST14
Intramembranei295 – 317Pore-forming; Name=P regionSequence analysisAdd BLAST23
Topological domaini318 – 326ExtracellularSequence analysis9
Transmembranei327 – 347Helical; Name=Segment S6Sequence analysisAdd BLAST21
Topological domaini348 – 1137CytoplasmicSequence analysisAdd BLAST790

Keywords - Cellular componenti

Membrane

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
ChainiPRO_00000541381 – 1137Calcium-activated potassium channel subunit alpha-1Add BLAST1137

Proteomic databases

PaxDbiQ8AYS8.

PTM databases

iPTMnetiQ8AYS8.

Expressioni

Gene expression databases

ExpressionAtlasiQ8AYS8. baseline and differential.

Interactioni

Subunit structurei

Homotetramer; which constitutes the calcium-activated potassium channel.By similarity

Binary interactionsi

Show more details

Protein-protein interaction databases

BioGridi675104. 110 interactors.
IntActiQ8AYS8. 107 interactors.
MINTiMINT-7260456.
STRINGi9031.ENSGALP00000007968.

Structurei

3D structure databases

ProteinModelPortaliQ8AYS8.
SMRiQ8AYS8.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini374 – 517RCK N-terminalAdd BLAST144

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Regioni515 – 535Segment S7Add BLAST21
Regioni572 – 592Segment S8Add BLAST21
Regioni636 – 640Heme-binding motif5
Regioni738 – 758Segment S9Add BLAST21
Regioni933 – 953Segment S10Add BLAST21

Motif

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Motifi311 – 314Selectivity for potassium4
Motifi904 – 926Calcium bowlAdd BLAST23

Domaini

The S0 segment is essential for the modulation by the accessory beta subunits.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

Keywords - Domaini

Transmembrane, Transmembrane helix

Phylogenomic databases

eggNOGiKOG1420. Eukaryota.
ENOG410YUX1. LUCA.
GeneTreeiENSGT00530000063026.
HOVERGENiHBG052222.
InParanoidiQ8AYS8.
KOiK04936.

Family and domain databases

InterProiView protein in InterPro
IPR024939. Ca-act_K_channel_Slo-1.
IPR005821. Ion_trans_dom.
IPR003929. K_chnl_BK_asu.
IPR016040. NAD(P)-bd_dom.
IPR028325. VG_K_chnl.
PANTHERiPTHR10027:SF37. PTHR10027:SF37. 1 hit.
PfamiView protein in Pfam
PF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
PRINTSiPR00169. KCHANNEL.
SUPFAMiSSF51735. SSF51735. 1 hit.

Sequences (10)i

Sequence statusi: Complete.

This entry describes 10 isoformsi produced by alternative splicing. AlignAdd to basket

Note: Additional isoforms seem to exist.
Isoform 1 (identifier: Q8AYS8-1) [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
MSNNINANNL NTDSSSSPVN VPKMDALIIP VTMEVPCDSR GQRMWWAFLA
60 70 80 90 100
SSMVTFFGGL FIILLWRTLK YLWTVCCHCG VKNKEAQKIN GGGDTQADGA
110 120 130 140 150
CKPTDEKEEN VAAEVGWMTS VKDWAGVMIS AQTLTGRVLV VLVFALSIGA
160 170 180 190 200
LVIYFIDSSN PIESCQNFYK DFTLQIDMAF NVFFLLYFGL RFIAANDKLW
210 220 230 240 250
FWLEVNSVVD FFTVPPVFVS VYLNRSWLGL RFLRALRLIQ FSEILQFLNI
260 270 280 290 300
LKTSNSIKLV NLCSIFISTW LTAAGFIHLV ENSGDPWENF QNNQQLTYWE
310 320 330 340 350
CVYLLMVTMS TVGYGDVYAK TTLGRLFMVF FILGGLAMFA SYVPEIIELI
360 370 380 390 400
GNRKKYGGSY SAVSGRKHIV VCGHITLESV SNFLKDFLHK DRDDVNVEIV
410 420 430 440 450
FLHNISPNLE LEALFKRHFT QVEFYQGSVL NPHDLARVKI ESADACLILA
460 470 480 490 500
NKYCADPDAE DASNIMRVIS IKNYHPKIRI ITQMLQYHNK AHLLNIPSWN
510 520 530 540 550
WKEGDDAICL AELKLGFIAQ SCLAPGLSTM LANLFSMRSF IKIEEDTWQK
560 570 580 590 600
YYLEGVANEM YTEYLSSAFV GLSFPAVCEL VFAKLKLLMI AIEYKSEKRE
610 620 630 640 650
SSILINPGNH VKIQEGTLGF FIASDAKEVK RAFFYCKACH DDITDPKRIK
660 670 680 690 700
KCGCKRLEDE QPSTLSPKKK QRNGGMRNSP NSSPKLMRHD PLLIPGNEQI
710 720 730 740 750
DNMDANVKKY DSTGMFHWCP AKDIEKVILT RSEAAMTVLS GHVVVCIFGD
760 770 780 790 800
VKSALIGLRN LVMPLRASNF HYHELKHIVF VGSLEYLRRE WETLHNFPKV
810 820 830 840 850
SILPGTPLSR ADLRAVNINL CDMCVILSAN QNNIDDASLQ DKECILASLN
860 870 880 890 900
IKSMQFDDSI GVLQANSQGF TPPGMDRSSP DNSPVHGLLR QPSITTGANI
910 920 930 940 950
PIITELVNDS NVQFLDQDDD DDPDTELYLT QPFACGTAFA VSVLDSLMSA
960 970 980 990 1000
TYFNDNILTL IRTLVTGGAT PELEALIAEE NALRGGYSTP QTLANRDRCR
1010 1020 1030 1040 1050
VAQLALYDGP FADLGDGGCY GDLFCKALKT YNMLCFGIYR LRDAHLSTPS
1060 1070 1080 1090 1100
QCTKRYVITN PPYEFELVPT DLIFCLMQFD HNAGQSRASL SHSSHSSYSS
1110 1120 1130
SKKSSSVHSI PSTANRPNRT KTRDSREKQK YVQEDRL
Length:1,137
Mass (Da):127,647
Last modified:April 13, 2004 - v2
Checksum:i40A9735E586F0BD1
GO
Isoform 2 (identifier: Q8AYS8-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     602-602: S → RSRKR

Show »
Length:1,141
Mass (Da):128,243
Checksum:i60A2C0EAB0534269
GO
Isoform 3 (identifier: Q8AYS8-3) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     657-657: L → PKMSIYKRMKLACCFDCGRSERDCSCMSGSVHSNMDTLERAFPLSSVSVNDCSTSLRAF

Show »
Length:1,195
Mass (Da):134,076
Checksum:i6AAD8F835A7A8177
GO
Isoform 4 (identifier: Q8AYS8-4) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1130-1137: KYVQEDRL → NSTRMNRMGQEKKWFTDEPDNAYPRNIQIKPMSTHMANQINQYKSTSSLIPPIREVEDEC

Show »
Length:1,189
Mass (Da):133,667
Checksum:iB334AAB3F4714EED
GO
Isoform 5 (identifier: Q8AYS8-5) [UniParc]FASTAAdd to basket
Also known as: IK

The sequence of this isoform differs from the canonical sequence as follows:
     906-906: L → LAKPGKLLPLVSISQEKNSGTQILMITEL

Show »
Length:1,165
Mass (Da):130,638
Checksum:i905BB9D1B2344E58
GO
Isoform 6 (identifier: Q8AYS8-6) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     657-657: L → IYF

Show »
Length:1,139
Mass (Da):127,957
Checksum:i45822D895211C704
GO
Isoform 7 (identifier: Q8AYS8-7) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1-17: MSNNINANNLNTDSSSS → MKPFEVSLPPPPPS

Show »
Length:1,134
Mass (Da):127,387
Checksum:i40B414AEFE0F1B55
GO
Isoform 8 (identifier: Q8AYS8-8) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     160-160: N → KSRTADSLI

Show »
Length:1,145
Mass (Da):128,505
Checksum:iC27FD559A611453C
GO
Isoform 9 (identifier: Q8AYS8-9) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     602-602: S → RSRKRYALFVTFPSNLNPTST

Show »
Length:1,157
Mass (Da):129,997
Checksum:i6284CAE9979B4A00
GO
Isoform 10 (identifier: Q8AYS8-10) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     687-687: M → MRFSCPFLP

Show »
Length:1,145
Mass (Da):128,595
Checksum:i61A433CB6C95073E
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti96Q → R in AAC60378 (PubMed:9178544).Curated1
Sequence conflicti397V → I in AAC60378 (PubMed:9178544).Curated1
Sequence conflicti409L → P in AAC35370 (PubMed:10362660).Curated1
Sequence conflicti522C → S in AAC60378 (PubMed:9178544).Curated1
Sequence conflicti712S → W in BAC20639 (PubMed:8755483).Curated1
Sequence conflicti937T → P in BAC20639 (PubMed:8755483).Curated1
Sequence conflicti941V → D in BAC20639 (PubMed:8755483).Curated1
Sequence conflicti1034L → F in AAC35370 (PubMed:10362660).Curated1

Alternative sequence

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Alternative sequenceiVSP_0099831 – 17MSNNI…DSSSS → MKPFEVSLPPPPPS in isoform 7. 1 PublicationAdd BLAST17
Alternative sequenceiVSP_009984160N → KSRTADSLI in isoform 8. 1 Publication1
Alternative sequenceiVSP_009985602S → RSRKR in isoform 2. 1 Publication1
Alternative sequenceiVSP_009986602S → RSRKRYALFVTFPSNLNPTS T in isoform 9. 1 Publication1
Alternative sequenceiVSP_009987657L → PKMSIYKRMKLACCFDCGRS ERDCSCMSGSVHSNMDTLER AFPLSSVSVNDCSTSLRAF in isoform 3. 2 Publications1
Alternative sequenceiVSP_009988657L → IYF in isoform 6. 1 Publication1
Alternative sequenceiVSP_009989687M → MRFSCPFLP in isoform 10. 1 Publication1
Alternative sequenceiVSP_009990906L → LAKPGKLLPLVSISQEKNSG TQILMITEL in isoform 5. 2 Publications1
Alternative sequenceiVSP_0099911130 – 1137KYVQEDRL → NSTRMNRMGQEKKWFTDEPD NAYPRNIQIKPMSTHMANQI NQYKSTSSLIPPIREVEDEC in isoform 4. 1 Publication8

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
U23821 mRNA. Translation: AAC60378.1.
U23823 mRNA. Translation: AAC60125.1.
U73189 mRNA. Translation: AAB17873.1.
AF087663 mRNA. Translation: AAC35370.1.
AB072618 mRNA. Translation: BAC20639.1.
RefSeqiNP_989555.1. NM_204224.1.
UniGeneiGga.3260.

Genome annotation databases

EnsembliENSGALT00000040502; ENSGALP00000039705; ENSGALG00000004980. [Q8AYS8-1]
GeneIDi374065.
KEGGigga:374065.

Keywords - Coding sequence diversityi

Alternative splicing

Similar proteinsi

Entry informationi

Entry nameiKCMA1_CHICK
AccessioniPrimary (citable) accession number: Q8AYS8
Secondary accession number(s): O12942
, O13110, O93569, Q98951, Q9PS76
Entry historyiIntegrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: April 13, 2004
Last modified: August 30, 2017
This is version 121 of the entry and version 2 of the sequence. See complete history.
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Miscellaneousi

Caution

It is uncertain whether Met-1 is the initiator or if the sequence starts further upstream.Curated

Keywords - Technical termi

Complete proteome, Reference proteome

Documents

  1. SIMILARITY comments
    Index of protein domains and families