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Q8AYS8 (KCMA1_CHICK) Reviewed, UniProtKB/Swiss-Prot

Last modified June 11, 2014. Version 96. Feed History...

Clusters with 100%, 90%, 50% identity | Documents (1) | Third-party data text xml rdf/xml gff fasta
to top of pageNames·Attributes·General annotation·Ontologies·Interactions·Alt products·Sequence annotation·Sequences·References·Cross-refs·Entry info·DocumentsCustomize order

Names and origin

Protein namesRecommended 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 names
Name:KCNMA1
Synonyms:KCNMA
OrganismGallus gallus (Chicken) [Reference proteome]
Taxonomic identifier9031 [NCBI]
Taxonomic lineageEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiTestudines + Archosauria groupArchosauriaDinosauriaSaurischiaTheropodaCoelurosauriaAvesNeognathaeGalliformesPhasianidaePhasianinaeGallus

Protein attributes

Sequence length1137 AA.
Sequence statusComplete.
Protein existenceEvidence at protein level

General annotation (Comments)

Function

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). Ref.6

Enzyme regulation

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

Subunit structure

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

Subcellular location

Membrane; Multi-pass membrane protein By similarity.

Domain

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.

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.

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.

The heme-binding motif mediates inhibition of channel activation by heme. Carbon monoxide-bound heme leads to increased channel activation By similarity.

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+.

Sequence similarities

Belongs to the potassium channel family. Calcium-activated (TC 1.A.1.3) subfamily. KCa1.1/KCNMA1 sub-subfamily. [View classification]

Contains 1 RCK N-terminal domain.

Caution

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

Alternative products

This entry describes 10 isoforms produced by alternative splicing. [Align] [Select]

Note: Additional isoforms seem to exist.
Isoform 1 (identifier: Q8AYS8-1)

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.
Isoform 2 (identifier: Q8AYS8-2)

The sequence of this isoform differs from the canonical sequence as follows:
     602-602: S → RSRKR
Isoform 3 (identifier: Q8AYS8-3)

The sequence of this isoform differs from the canonical sequence as follows:
     657-657: L → PKMSIYKRMKLACCFDCGRSERDCSCMSGSVHSNMDTLERAFPLSSVSVNDCSTSLRAF
Isoform 4 (identifier: Q8AYS8-4)

The sequence of this isoform differs from the canonical sequence as follows:
     1130-1137: KYVQEDRL → NSTRMNRMGQEKKWFTDEPDNAYPRNIQIKPMSTHMANQINQYKSTSSLIPPIREVEDEC
Isoform 5 (identifier: Q8AYS8-5)

Also known as: IK;

The sequence of this isoform differs from the canonical sequence as follows:
     906-906: L → LAKPGKLLPLVSISQEKNSGTQILMITEL
Isoform 6 (identifier: Q8AYS8-6)

The sequence of this isoform differs from the canonical sequence as follows:
     657-657: L → IYF
Isoform 7 (identifier: Q8AYS8-7)

The sequence of this isoform differs from the canonical sequence as follows:
     1-17: MSNNINANNLNTDSSSS → MKPFEVSLPPPPPS
Isoform 8 (identifier: Q8AYS8-8)

The sequence of this isoform differs from the canonical sequence as follows:
     160-160: N → KSRTADSLI
Isoform 9 (identifier: Q8AYS8-9)

The sequence of this isoform differs from the canonical sequence as follows:
     602-602: S → RSRKRYALFVTFPSNLNPTST
Isoform 10 (identifier: Q8AYS8-10)

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

Sequence annotation (Features)

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifier

Molecule processing

Chain1 – 11371137Calcium-activated potassium channel subunit alpha-1
PRO_0000054138

Regions

Topological domain1 – 4444Extracellular Potential
Transmembrane45 – 6521Helical; Name=Segment S0; Potential
Topological domain66 – 13772Cytoplasmic Potential
Transmembrane138 – 15821Helical; Name=Segment S1; Potential
Topological domain159 – 17315Extracellular Potential
Transmembrane174 – 19421Helical; Name=Segment S2; Potential
Topological domain195 – 1984Cytoplasmic Potential
Transmembrane199 – 21921Helical; Name=Segment S3; Potential
Topological domain220 – 2234Extracellular Potential
Transmembrane224 – 24421Helical; Voltage-sensor; Name=Segment S4; Potential
Topological domain245 – 25915Cytoplasmic Potential
Transmembrane260 – 28021Helical; Name=Segment S5; Potential
Topological domain281 – 29414Extracellular Potential
Intramembrane295 – 31723Pore-forming; Name=P region; Potential
Topological domain318 – 3269Extracellular Potential
Transmembrane327 – 34721Helical; Name=Segment S6; Potential
Topological domain348 – 1137790Cytoplasmic Potential
Domain374 – 517144RCK N-terminal
Region515 – 53521Segment S7
Region572 – 59221Segment S8
Region636 – 6405Heme-binding motif
Region738 – 75821Segment S9
Region933 – 95321Segment S10
Motif311 – 3144Selectivity for potassium
Motif904 – 92623Calcium bowl

Sites

Metal binding3981Magnesium By similarity
Metal binding4211Magnesium By similarity
Metal binding4231Magnesium By similarity
Metal binding9131Calcium; via carbonyl oxygen By similarity
Metal binding9161Calcium; via carbonyl oxygen By similarity
Metal binding9191Calcium By similarity
Metal binding9211Calcium By similarity

Natural variations

Alternative sequence1 – 1717MSNNI…DSSSS → MKPFEVSLPPPPPS in isoform 7.
VSP_009983
Alternative sequence1601N → KSRTADSLI in isoform 8.
VSP_009984
Alternative sequence6021S → RSRKR in isoform 2.
VSP_009985
Alternative sequence6021S → RSRKRYALFVTFPSNLNPTS T in isoform 9.
VSP_009986
Alternative sequence6571L → PKMSIYKRMKLACCFDCGRS ERDCSCMSGSVHSNMDTLER AFPLSSVSVNDCSTSLRAF in isoform 3.
VSP_009987
Alternative sequence6571L → IYF in isoform 6.
VSP_009988
Alternative sequence6871M → MRFSCPFLP in isoform 10.
VSP_009989
Alternative sequence9061L → LAKPGKLLPLVSISQEKNSG TQILMITEL in isoform 5.
VSP_009990
Alternative sequence1130 – 11378KYVQEDRL → NSTRMNRMGQEKKWFTDEPD NAYPRNIQIKPMSTHMANQI NQYKSTSSLIPPIREVEDEC in isoform 4.
VSP_009991

Experimental info

Sequence conflict961Q → R in AAC60378. Ref.1
Sequence conflict3971V → I in AAC60378. Ref.1
Sequence conflict4091L → P in AAC35370. Ref.4
Sequence conflict5221C → S in AAC60378. Ref.1
Sequence conflict7121S → W in BAC20639. Ref.5
Sequence conflict9371T → P in BAC20639. Ref.5
Sequence conflict9411V → D in BAC20639. Ref.5
Sequence conflict10341L → F in AAC35370. Ref.4

Sequences

Sequence LengthMass (Da)Tools
Isoform 1 [UniParc].

Last modified April 13, 2004. Version 2.
Checksum: 40A9735E586F0BD1

FASTA1,137127,647
        10         20         30         40         50         60 
MSNNINANNL NTDSSSSPVN VPKMDALIIP VTMEVPCDSR GQRMWWAFLA SSMVTFFGGL 

        70         80         90        100        110        120 
FIILLWRTLK YLWTVCCHCG VKNKEAQKIN GGGDTQADGA CKPTDEKEEN VAAEVGWMTS 

       130        140        150        160        170        180 
VKDWAGVMIS AQTLTGRVLV VLVFALSIGA LVIYFIDSSN PIESCQNFYK DFTLQIDMAF 

       190        200        210        220        230        240 
NVFFLLYFGL RFIAANDKLW FWLEVNSVVD FFTVPPVFVS VYLNRSWLGL RFLRALRLIQ 

       250        260        270        280        290        300 
FSEILQFLNI LKTSNSIKLV NLCSIFISTW LTAAGFIHLV ENSGDPWENF QNNQQLTYWE 

       310        320        330        340        350        360 
CVYLLMVTMS TVGYGDVYAK TTLGRLFMVF FILGGLAMFA SYVPEIIELI GNRKKYGGSY 

       370        380        390        400        410        420 
SAVSGRKHIV VCGHITLESV SNFLKDFLHK DRDDVNVEIV FLHNISPNLE LEALFKRHFT 

       430        440        450        460        470        480 
QVEFYQGSVL NPHDLARVKI ESADACLILA NKYCADPDAE DASNIMRVIS IKNYHPKIRI 

       490        500        510        520        530        540 
ITQMLQYHNK AHLLNIPSWN WKEGDDAICL AELKLGFIAQ SCLAPGLSTM LANLFSMRSF 

       550        560        570        580        590        600 
IKIEEDTWQK YYLEGVANEM YTEYLSSAFV GLSFPAVCEL VFAKLKLLMI AIEYKSEKRE 

       610        620        630        640        650        660 
SSILINPGNH VKIQEGTLGF FIASDAKEVK RAFFYCKACH DDITDPKRIK KCGCKRLEDE 

       670        680        690        700        710        720 
QPSTLSPKKK QRNGGMRNSP NSSPKLMRHD PLLIPGNEQI DNMDANVKKY DSTGMFHWCP 

       730        740        750        760        770        780 
AKDIEKVILT RSEAAMTVLS GHVVVCIFGD VKSALIGLRN LVMPLRASNF HYHELKHIVF 

       790        800        810        820        830        840 
VGSLEYLRRE WETLHNFPKV SILPGTPLSR ADLRAVNINL CDMCVILSAN QNNIDDASLQ 

       850        860        870        880        890        900 
DKECILASLN IKSMQFDDSI GVLQANSQGF TPPGMDRSSP DNSPVHGLLR QPSITTGANI 

       910        920        930        940        950        960 
PIITELVNDS NVQFLDQDDD DDPDTELYLT QPFACGTAFA VSVLDSLMSA TYFNDNILTL 

       970        980        990       1000       1010       1020 
IRTLVTGGAT PELEALIAEE NALRGGYSTP QTLANRDRCR VAQLALYDGP FADLGDGGCY 

      1030       1040       1050       1060       1070       1080 
GDLFCKALKT YNMLCFGIYR LRDAHLSTPS QCTKRYVITN PPYEFELVPT DLIFCLMQFD 

      1090       1100       1110       1120       1130 
HNAGQSRASL SHSSHSSYSS SKKSSSVHSI PSTANRPNRT KTRDSREKQK YVQEDRL 

« Hide

Isoform 2 [UniParc].

Checksum: 60A2C0EAB0534269
Show »

FASTA1,141128,243
Isoform 3 [UniParc].

Checksum: 6AAD8F835A7A8177
Show »

FASTA1,195134,076
Isoform 4 [UniParc].

Checksum: B334AAB3F4714EED
Show »

FASTA1,189133,667
Isoform 5 (IK) [UniParc].

Checksum: 905BB9D1B2344E58
Show »

FASTA1,165130,638
Isoform 6 [UniParc].

Checksum: 45822D895211C704
Show »

FASTA1,139127,957
Isoform 7 [UniParc].

Checksum: 40B414AEFE0F1B55
Show »

FASTA1,134127,387
Isoform 8 [UniParc].

Checksum: C27FD559A611453C
Show »

FASTA1,145128,505
Isoform 9 [UniParc].

Checksum: 6284CAE9979B4A00
Show »

FASTA1,157129,997
Isoform 10 [UniParc].

Checksum: 61A433CB6C95073E
Show »

FASTA1,145128,595

References

[1]"CSlo encodes calcium-activated potassium channels in the chick's cochlea."
Jiang G.J., Zidanic M., Michaels R.L., Michael T.H., Griguer C., Fuchs P.A.
Proc. R. Soc. B 264:731-737(1997) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1), NUCLEOTIDE SEQUENCE OF 398-1137 (ISOFORM 4).
Strain: Leghorn.
Tissue: Cochlear duct.
[2]"Distribution of Ca2+-activated K+ channel isoforms along the tonotopic gradient of the chicken's cochlea."
Rosenblatt K.P., Sun Z.-P., Heller S., Hudspeth A.J.
Neuron 19:1061-1075(1997) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORMS 1; 2; 3; 4; 5; 6; 7; 8; 9 AND 10).
Strain: White leghorn.
Tissue: Brain.
[3]"Molecular biology and electrophysiology of calcium-activated potassium channels from lens epithelium."
Rae J.L., Shepard A.R.
Curr. Eye Res. 17:264-275(1998) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] (ISOFORM 1).
Strain: White leghorn.
Tissue: Lens epithelium.
[4]"Characterization of a newly found stretch-activated KCa,ATP channel in cultured chick ventricular myocytes."
Kawakubo T., Naruse K., Matsubara T., Hotta N., Sokabe M.
Am. J. Physiol. 276:H1827-H1838(1999) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 24-1137 (ISOFORM 3).
[5]"Posttranslational regulation of Ca(2+)-activated K+ currents by a target-derived factor in developing parasympathetic neurons."
Subramony P., Raucher S., Dryer L., Dryer S.E.
Neuron 17:115-124(1996) [PubMed] [Europe PMC] [Abstract]
Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 710-973 (ISOFORM 5).
[6]"A molecular mechanism for electrical tuning of cochlear hair cells."
Ramanathan K., Michael T.H., Jiang G.-J., Hiel H., Fuchs P.A.
Science 283:215-217(1999) [PubMed] [Europe PMC] [Abstract]
Cited for: FUNCTION.
+Additional computationally mapped references.

Cross-references

Sequence databases

EMBL
GenBank
DDBJ
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.
RefSeqNP_989555.1. NM_204224.1.
UniGeneGga.3260.

3D structure databases

ProteinModelPortalQ8AYS8.
ModBaseSearch...
MobiDBSearch...

Protein-protein interaction databases

BioGrid675104. 110 interactions.
IntActQ8AYS8. 107 interactions.
MINTMINT-7260456.

Proteomic databases

PaxDbQ8AYS8.
PRIDEQ8AYS8.

Protocols and materials databases

StructuralBiologyKnowledgebaseSearch...

Genome annotation databases

GeneID374065.
KEGGgga:374065.

Organism-specific databases

CTD3778.

Phylogenomic databases

eggNOGCOG1226.
HOVERGENHBG052222.
InParanoidQ8AYS8.
KOK04936.

Family and domain databases

Gene3D3.40.50.720. 1 hit.
InterProIPR005821. Ion_trans_dom.
IPR003091. K_chnl.
IPR003929. K_chnl_Ca-activ_BK_asu.
IPR016040. NAD(P)-bd_dom.
IPR003148. RCK_N.
[Graphical view]
PfamPF03493. BK_channel_a. 1 hit.
PF00520. Ion_trans. 1 hit.
PF02254. TrkA_N. 1 hit.
[Graphical view]
PRINTSPR01449. BKCHANNELA.
PR00169. KCHANNEL.
ProtoNetSearch...

Other

NextBio20813586.
PROQ8AYS8.

Entry information

Entry nameKCMA1_CHICK
AccessionPrimary (citable) accession number: Q8AYS8
Secondary accession number(s): O12942 expand/collapse secondary AC list , O13110, O93569, Q98951, Q9PS76
Entry history
Integrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: April 13, 2004
Last modified: June 11, 2014
This is version 96 of the entry and version 2 of the sequence. [Complete history]
Entry statusReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program

Relevant documents

SIMILARITY comments

Index of protein domains and families