Skip Header

You are using a version of browser that may not display all the features of this website. Please consider upgrading your browser.
Protein

Calcium-activated potassium channel subunit alpha-1

Gene

KCNMA1

Organism
Oryctolagus cuniculus (Rabbit)
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)LengthDescriptionGraphical viewFeature identifierActions
Metal bindingi440 – 4401MagnesiumBy similarity
Metal bindingi463 – 4631MagnesiumBy similarity
Metal bindingi465 – 4651MagnesiumBy similarity
Metal bindingi955 – 9551Calcium; via carbonyl oxygenBy similarity
Metal bindingi958 – 9581Calcium; via carbonyl oxygenBy similarity
Metal bindingi961 – 9611CalciumBy similarity
Metal bindingi963 – 9631CalciumBy 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:
RbSlo
Short name:
Slo homolog
Gene namesi
Name:KCNMA1
Synonyms:KCNMA
OrganismiOryctolagus cuniculus (Rabbit)
Taxonomic identifieri9986 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresGliresLagomorphaLeporidaeOryctolagus
Proteomesi
  • UP000001811 Componenti: Unplaced

Subcellular locationi

Isoform 4 :

Topology

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Topological domaini1 – 8787ExtracellularSequence analysisAdd
BLAST
Transmembranei88 – 10821Helical; Name=Segment S0Sequence analysisAdd
BLAST
Topological domaini109 – 17971CytoplasmicSequence analysisAdd
BLAST
Transmembranei180 – 20021Helical; Name=Segment S1Sequence analysisAdd
BLAST
Topological domaini201 – 21515ExtracellularSequence analysisAdd
BLAST
Transmembranei216 – 23621Helical; Name=Segment S2Sequence analysisAdd
BLAST
Topological domaini237 – 2404CytoplasmicSequence analysis
Transmembranei241 – 26121Helical; Name=Segment S3Sequence analysisAdd
BLAST
Topological domaini262 – 2654ExtracellularSequence analysis
Transmembranei266 – 28621Helical; Voltage-sensor; Name=Segment S4Sequence analysisAdd
BLAST
Topological domaini287 – 30115CytoplasmicSequence analysisAdd
BLAST
Transmembranei302 – 32221Helical; Name=Segment S5Sequence analysisAdd
BLAST
Topological domaini323 – 33614ExtracellularSequence analysisAdd
BLAST
Intramembranei337 – 35923Pore-forming; Name=P regionSequence analysisAdd
BLAST
Topological domaini360 – 3689ExtracellularSequence analysis
Transmembranei369 – 38921Helical; Name=Segment S6Sequence analysisAdd
BLAST
Topological domaini390 – 1179790CytoplasmicSequence analysisAdd
BLAST

GO - Cellular componenti

Complete GO annotation...

Keywords - Cellular componenti

Cell membrane, Endoplasmic reticulum, Membrane

PTM / Processingi

Molecule processing

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Chaini1 – 11791179Calcium-activated potassium channel subunit alpha-1PRO_0000054136Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Lipidationi119 – 1191S-palmitoyl cysteineBy similarity
Lipidationi120 – 1201S-palmitoyl cysteineBy similarity
Lipidationi122 – 1221S-palmitoyl cysteineBy similarity
Modified residuei706 – 7061PhosphothreonineBy similarity
Modified residuei708 – 7081PhosphoserineBy similarity
Modified residuei721 – 7211PhosphoserineBy similarity
Modified residuei725 – 7251PhosphoserineBy similarity
Modified residuei913 – 9131PhosphothreonineBy similarity
Modified residuei921 – 9211PhosphoserineBy similarity
Modified residuei925 – 9251PhosphoserineBy 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

PRIDEiQ9BG98.

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

ProteinModelPortaliQ9BG98.
ModBaseiSearch...
MobiDBiSearch...

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini416 – 559144RCK N-terminalAdd
BLAST

Region

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Regioni557 – 57721Segment S7Add
BLAST
Regioni614 – 63421Segment S8Add
BLAST
Regioni678 – 6825Heme-binding motif
Regioni780 – 80021Segment S9Add
BLAST
Regioni975 – 99521Segment S10Add
BLAST

Motif

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Motifi353 – 3564Selectivity for potassium
Motifi946 – 96823Calcium bowlAdd
BLAST

Compositional bias

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Compositional biasi4 – 107Poly-Gly
Compositional biasi13 – 2412Poly-GlyAdd
BLAST
Compositional biasi41 – 6121Poly-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

HOVERGENiHBG052222.
InParanoidiQ9BG98.
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.

Sequences (4)i

Sequence statusi: Complete.

This entry describes 4 isoformsi produced by alternative splicing. AlignAdd to basket

Note: May be partially controlled by hormonal stress. Additional isoforms seem to exist.
Isoform 1 (identifier: Q9BG98-1) [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
MANGGGGGGG SSGGGGGGGG GGSGLRMSSN IHASHLSLDA SSSSSSSSSS
60 70 80 90 100
SSSSSSSSSS SVHEPKMDAL IIPVTMEVPC DSRGQRMWWA FLASSMVTFF
110 120 130 140 150
GGLFIILLWR TLKYLWTVCC HCGGKAKEAQ KINNGSSQAD GTLKPVDEKE
160 170 180 190 200
EAVAAEVGWM TSVKDWAGVM ISAQTLTGRV LVVLVFALSI GALVIYFIDS
210 220 230 240 250
SNPIESCQNF YKDFTLQIDM AFNVFFLLYF GLRFIAANDK LWFWLEVNSV
260 270 280 290 300
VDFFTVPPVF VSVYLNRSWL GLRFLRALRL IQFSEILQFL NILKTSNSIK
310 320 330 340 350
LVNLLSIFIS TWLTAAGFIH LVENSGDPWE NFQNNQALTY WECVYLLMVT
360 370 380 390 400
MSTVGYGDVY AKTTLGRLFM VFFILGGLAM FASYVPEIIE LIGNRKKYGG
410 420 430 440 450
SYSAVSGRKH IVVCGHITLE SVSNFLKDFL HKDRDDVNVE IVFLHNISPN
460 470 480 490 500
LELEALFKRH FTQVEFYQGS VLNPHDLARV KIESADACLI LANKYCADPD
510 520 530 540 550
AEDASNIMRV ISIKNYHPKI RIITQMLQYH NKAHLLNIPS WNWKEGDDAI
560 570 580 590 600
CLAELKLGFI AQSCLAQGLS TMLANLFSMR SFIKIEEDTW QKYYLEGVSN
610 620 630 640 650
EMYTEYLSSA FVGLSFPTVC ELCFVKLKLL MIAIEYKSAN RESRILINPG
660 670 680 690 700
NHLKIQEGTL GFFIASDAKE VKRAFFYCKA CHDDITDPKR IKKCGCKRLE
710 720 730 740 750
DEQPSTLSPK KKQRNGGMRN SPNSSPKLMR HDPLLIPGND QIDNMDSNVK
760 770 780 790 800
KYDSTGMFHW CAPKEIEKVI LTRSEAAMTV LSGHVVVCIF GDVSSALIGL
810 820 830 840 850
RNLVMPLRAS NFHYHELKHI VFVGSIEYLK REWETLHNFP KVSILPGTPL
860 870 880 890 900
SRADLRAVNI NLCDMCVILS ANQNNIDDTS LQDKECILAS LNIKSMQFDD
910 920 930 940 950
SIGVLQANSQ GFTPPGMDRS SPDNSPVHGM LRQPSITTGV NIPIITELVN
960 970 980 990 1000
DTNVQFLDQD DDDDPDTELY LTQPFACGTA FAVSVLDSLM SATYFNDNIL
1010 1020 1030 1040 1050
TLIRTLVTGG ATPELEALIA EENALRGGYS TPQTLANRDR CRVAQLALLD
1060 1070 1080 1090 1100
GPFADLGDGG CYGDLFCKAL KTYNMLCFGI YRLRDAHLST PSQCTKRYVI
1110 1120 1130 1140 1150
TNPPYEFELV PTDLIFCLMQ FDHNAGQSRA SLSHSSHSSQ SSSKKSSSVH
1160 1170
SIPSTANRQN RPKSRESRDK QKYVQEERL
Length:1,179
Mass (Da):130,925
Last modified:June 1, 2001 - v1
Checksum:i9354488A6BB3B7E2
GO
Isoform 2 (identifier: Q9BG98-2) [UniParc]FASTAAdd to basket

The sequence of this isoform differs from the canonical sequence as follows:
     1172-1179: KYVQEERL → NEKKWFTDEPDNAYPRNIQIKPMSTHMANQINQYKSTSSLIPPIREVEDEC

Show »
Length:1,222
Mass (Da):135,869
Checksum:i89FA9D2993C56287
GO
Isoform 3 (identifier: Q9BG98-3) [UniParc]FASTAAdd to basket
Also known as: rbslo1

The sequence of this isoform differs from the canonical sequence as follows:
     699-699: L → PKMSIYKRMRRACCFGCGRSERDCSCMSGRVRGHVDTLGRAFPLSSVSVSDCCTRFRAF

Show »
Length:1,237
Mass (Da):137,437
Checksum:i0AF0FA122F6B8293
GO
Isoform 4 (identifier: Q9BG98-4) [UniParc]FASTAAdd to basket
Also known as: rbslo2

The sequence of this isoform differs from the canonical sequence as follows:
     848-862: TPLSRADLRAVNINL → QGMHLGVTQHQIYAV
     863-1179: Missing.

Show »
Length:862
Mass (Da):96,076
Checksum:iBB45DB448A77B01B
GO

Sequence cautioni

The sequence AAF17562 differs from that shown. Reason: Erroneous initiation. Curated
The sequence BAA23747 differs from that shown. Reason: Erroneous initiation. Curated

Experimental Info

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Sequence conflicti42 – 421Missing in BAA23747 (Ref. 3) Curated
Sequence conflicti234 – 2341F → S in BAA23747 (Ref. 3) Curated
Sequence conflicti422 – 4221V → F in BAA23747 (Ref. 3) Curated
Sequence conflicti532 – 5321K → M in BAA23747 (Ref. 3) Curated
Sequence conflicti774 – 7741S → T in AAF17562 (PubMed:9362339).Curated
Sequence conflicti874 – 8741N → D in BAA23747 (Ref. 3) Curated
Sequence conflicti1075 – 10751M → I in AAF17562 (PubMed:9362339).Curated
Sequence conflicti1111 – 11111P → A in BAA23747 (Ref. 3) Curated

Alternative sequence

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Alternative sequencei699 – 6991L → PKMSIYKRMRRACCFGCGRS ERDCSCMSGRVRGHVDTLGR AFPLSSVSVSDCCTRFRAF in isoform 3. 1 PublicationVSP_009966
Alternative sequencei848 – 86215TPLSR…VNINL → QGMHLGVTQHQIYAV in isoform 4. 1 PublicationVSP_009968Add
BLAST
Alternative sequencei863 – 1179317Missing in isoform 4. 1 PublicationVSP_009969Add
BLAST
Alternative sequencei1172 – 11798KYVQEERL → NEKKWFTDEPDNAYPRNIQI KPMSTHMANQINQYKSTSSL IPPIREVEDEC in isoform 2. 1 PublicationVSP_009967

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF321818 mRNA. Translation: AAK09380.1.
AF201702 mRNA. Translation: AAF17562.1. Different initiation.
AB009312 mRNA. Translation: BAA23747.1. Different initiation.
RefSeqiNP_001075539.1. NM_001082070.1.
UniGeneiOcu.2187.

Genome annotation databases

GeneIDi100008745.
KEGGiocu:100008745.

Keywords - Coding sequence diversityi

Alternative splicing

Cross-referencesi

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF321818 mRNA. Translation: AAK09380.1.
AF201702 mRNA. Translation: AAF17562.1. Different initiation.
AB009312 mRNA. Translation: BAA23747.1. Different initiation.
RefSeqiNP_001075539.1. NM_001082070.1.
UniGeneiOcu.2187.

3D structure databases

ProteinModelPortaliQ9BG98.
ModBaseiSearch...
MobiDBiSearch...

Proteomic databases

PRIDEiQ9BG98.

Protocols and materials databases

Structural Biology KnowledgebaseSearch...

Genome annotation databases

GeneIDi100008745.
KEGGiocu:100008745.

Organism-specific databases

CTDi3778.

Phylogenomic databases

HOVERGENiHBG052222.
InParanoidiQ9BG98.
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...

Entry informationi

Entry nameiKCMA1_RABIT
AccessioniPrimary (citable) accession number: Q9BG98
Secondary accession number(s): O46371, Q9TT88
Entry historyi
Integrated into UniProtKB/Swiss-Prot: April 13, 2004
Last sequence update: June 1, 2001
Last modified: January 20, 2016
This is version 104 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.