KCMA1_XENLA
ID KCMA1_XENLA Reviewed; 1196 AA.
AC Q90ZC7;
DT 13-APR-2004, integrated into UniProtKB/Swiss-Prot.
DT 01-DEC-2001, sequence version 1.
DT 03-AUG-2022, entry version 108.
DE RecName: Full=Calcium-activated potassium channel subunit alpha-1;
DE AltName: Full=BK channel;
DE AltName: Full=BKCA alpha;
DE AltName: Full=Calcium-activated potassium channel, subfamily M subunit alpha-1;
DE AltName: Full=K(VCA)alpha;
DE AltName: Full=KCa1.1;
DE AltName: Full=Maxi K channel;
DE Short=MaxiK;
DE AltName: Full=Slo-alpha;
DE AltName: Full=Slo1;
DE AltName: Full=Slowpoke homolog;
DE Short=Slo homolog;
DE Short=xSlo;
GN Name=kcnma1; Synonyms=kcnma, xslo;
OS Xenopus laevis (African clawed frog).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia;
OC Batrachia; Anura; Pipoidea; Pipidae; Xenopodinae; Xenopus; Xenopus.
OX NCBI_TaxID=8355;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA] (ISOFORMS 1; 2; 3; 4 AND 5), TISSUE SPECIFICITY,
RP AND DEVELOPMENTAL STAGE.
RX PubMed=12867527; DOI=10.1152/jn.00398.2003;
RA Kukuljan M., Taylor A., Chouinard H., Olguin P., Rojas C.V., Ribera A.B.;
RT "Selective regulation of xSlo splice variants during Xenopus
RT embryogenesis.";
RL J. Neurophysiol. 90:3352-3360(2003).
CC -!- FUNCTION: Potassium channel activated by both membrane depolarization
CC or increase in cytosolic Ca(2+) that mediates export of K(+). It is
CC also activated by the concentration of cytosolic Mg(2+). Its activation
CC dampens the excitatory events that elevate the cytosolic Ca(2+)
CC concentration and/or depolarize the cell membrane. It therefore
CC contributes to repolarization of the membrane potential. Plays a key
CC role in controlling excitability in a number of systems, such as
CC regulation of the contraction of smooth muscle, the tuning of hair
CC cells in the cochlea, regulation of transmitter release, and innate
CC immunity. In smooth muscles, its activation by high level of Ca(2+),
CC caused by ryanodine receptors in the sarcoplasmic reticulum, regulates
CC the membrane potential. In cochlea cells, its number and kinetic
CC properties partly determine the characteristic frequency of each hair
CC cell and thereby helps to establish a tonotopic map. Highly sensitive
CC to both iberiotoxin (IbTx) and charybdotoxin (CTX) (By similarity).
CC {ECO:0000250}.
CC -!- ACTIVITY REGULATION: Ethanol and carbon monoxide-bound heme increase
CC channel activation. Heme inhibits channel activation (By similarity).
CC {ECO:0000250}.
CC -!- SUBUNIT: Homotetramer; which constitutes the calcium-activated
CC potassium channel. {ECO:0000250}.
CC -!- SUBCELLULAR LOCATION: Membrane {ECO:0000250}; Multi-pass membrane
CC protein {ECO:0000250}.
CC -!- ALTERNATIVE PRODUCTS:
CC Event=Alternative splicing; Named isoforms=5;
CC Comment=Additional isoforms seem to exist.;
CC Name=1;
CC IsoId=Q90ZC7-1; Sequence=Displayed;
CC Name=2; Synonyms=xSlo15;
CC IsoId=Q90ZC7-2; Sequence=VSP_009992;
CC Name=3; Synonyms=xSlo56;
CC IsoId=Q90ZC7-3; Sequence=VSP_009993;
CC Name=4; Synonyms=xSlo59;
CC IsoId=Q90ZC7-4; Sequence=VSP_009994;
CC Name=5; Synonyms=xSlo99;
CC IsoId=Q90ZC7-5; Sequence=VSP_009995;
CC -!- TISSUE SPECIFICITY: Expressed in both the somites and neural tube of 1
CC day embryos. Within the nervous system, it is restricted to dorsal
CC parts, and expressed centrally in regions dedicated to processing of
CC sensory information. Six hours later, it is expressed segmentally
CC within the somites. At this time, it is expressed in a primary sensory
CC organ, the trigeminal ganglion. By 2 days, it is also expressed in
CC other primary sensory organs, such as the otic vesicle, and the eye.
CC Within the retina, it is expressed to an internal layer. In the
CC developing otic vesicle, it is abundantly expressed near the apical
CC surface. Isoform 3 is neural-specific, and is only expressed during
CC late stages of neuronal differentiation. {ECO:0000269|PubMed:12867527}.
CC -!- DEVELOPMENTAL STAGE: Expressed during embryogenesis before
CC differentiation of excitable tissues. {ECO:0000269|PubMed:12867527}.
CC -!- DOMAIN: The S0 segment is essential for the modulation by the accessory
CC beta subunits. {ECO:0000250}.
CC -!- DOMAIN: The S4 segment, which is characterized by a series of
CC positively charged amino acids at every third position, is part of the
CC voltage-sensor. {ECO:0000250}.
CC -!- DOMAIN: The pore-forming domain (also referred as P region) is imbedded
CC into the membrane, and forms the selectivity filter of the pore. It
CC contains the signature sequence of potassium channels that displays
CC selectivity to potassium (By similarity). {ECO:0000250}.
CC -!- DOMAIN: The RCK N-terminal domain mediates the homotetramerization,
CC thereby promoting the assembly of monomers into functional potassium
CC channel. It includes binding sites for Ca(2+) and Mg(2+) (By
CC similarity). {ECO:0000250}.
CC -!- DOMAIN: The calcium bowl constitutes one of the Ca(2+) sensors and
CC probably acts as a Ca(2+)-binding site. There are however other Ca(2+)
CC sensors regions required for activation of the channel (By similarity).
CC {ECO:0000250}.
CC -!- DOMAIN: The heme-binding motif mediates inhibition of channel
CC activation by heme. Carbon monoxide-bound heme leads to increased
CC channel activation (By similarity). {ECO:0000250}.
CC -!- MISCELLANEOUS: The protein was initially thought to contain two
CC functionally distinct parts: The core channel (from the N-terminus to
CC the S9 segment) that mediates the channel activity, and the cytoplasmic
CC tail (from the S9 segment to the C-terminus) that mediates the calcium
CC sensing. The situation is however more complex, since the core channel
CC contains binding sites for Ca(2+) and Mg(2+).
CC -!- SIMILARITY: Belongs to the potassium channel family. Calcium-activated
CC (TC 1.A.1.3) subfamily. KCa1.1/KCNMA1 sub-subfamily. {ECO:0000305}.
CC -!- CAUTION: It is uncertain whether Met-1 is the initiator or if the
CC sequence starts further upstream. {ECO:0000305}.
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DR EMBL; AF274053; AAK69394.1; -; mRNA.
DR RefSeq; NP_001079159.1; NM_001085690.1. [Q90ZC7-1]
DR AlphaFoldDB; Q90ZC7; -.
DR SMR; Q90ZC7; -.
DR GeneID; 373712; -.
DR KEGG; xla:373712; -.
DR CTD; 373712; -.
DR Xenbase; XB-GENE-922343; kcnma1.L.
DR OrthoDB; 124461at2759; -.
DR Proteomes; UP000186698; Chromosome 7L.
DR Bgee; 373712; Expressed in brain and 15 other tissues.
DR GO; GO:0016021; C:integral component of membrane; IEA:UniProtKB-KW.
DR GO; GO:0060072; F:large conductance calcium-activated potassium channel activity; IEA:InterPro.
DR GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR GO; GO:0005244; F:voltage-gated ion channel activity; IEA:UniProtKB-KW.
DR GO; GO:0034765; P:regulation of ion transmembrane transport; IEA:UniProtKB-KW.
DR InterPro; IPR024939; Ca-act_K_channel_Slo-1.
DR InterPro; IPR005821; Ion_trans_dom.
DR InterPro; IPR003929; K_chnl_BK_asu.
DR InterPro; IPR036291; NAD(P)-bd_dom_sf.
DR PANTHER; PTHR10027:SF28; PTHR10027:SF28; 2.
DR Pfam; PF03493; BK_channel_a; 1.
DR Pfam; PF00520; Ion_trans; 1.
DR SUPFAM; SSF51735; SSF51735; 1.
PE 2: Evidence at transcript level;
KW Alternative splicing; Calcium; Ion channel; Ion transport; Magnesium;
KW Membrane; Metal-binding; Potassium; Potassium channel; Potassium transport;
KW Reference proteome; Transmembrane; Transmembrane helix; Transport;
KW Voltage-gated channel.
FT CHAIN 1..1196
FT /note="Calcium-activated potassium channel subunit alpha-1"
FT /id="PRO_0000054139"
FT TOPO_DOM 1..52
FT /note="Extracellular"
FT /evidence="ECO:0000255"
FT TRANSMEM 53..73
FT /note="Helical; Name=Segment S0"
FT /evidence="ECO:0000255"
FT TOPO_DOM 74..146
FT /note="Cytoplasmic"
FT /evidence="ECO:0000255"
FT TRANSMEM 147..167
FT /note="Helical; Name=Segment S1"
FT /evidence="ECO:0000255"
FT TOPO_DOM 168..182
FT /note="Extracellular"
FT /evidence="ECO:0000255"
FT TRANSMEM 183..203
FT /note="Helical; Name=Segment S2"
FT /evidence="ECO:0000255"
FT TOPO_DOM 204..207
FT /note="Cytoplasmic"
FT /evidence="ECO:0000255"
FT TRANSMEM 208..228
FT /note="Helical; Name=Segment S3"
FT /evidence="ECO:0000255"
FT TOPO_DOM 229..232
FT /note="Extracellular"
FT /evidence="ECO:0000255"
FT TRANSMEM 233..253
FT /note="Helical; Voltage-sensor; Name=Segment S4"
FT /evidence="ECO:0000255"
FT TOPO_DOM 254..268
FT /note="Cytoplasmic"
FT /evidence="ECO:0000255"
FT TRANSMEM 269..289
FT /note="Helical; Name=Segment S5"
FT /evidence="ECO:0000255"
FT TOPO_DOM 290..303
FT /note="Extracellular"
FT /evidence="ECO:0000255"
FT INTRAMEM 304..326
FT /note="Pore-forming; Name=P region"
FT /evidence="ECO:0000255"
FT TOPO_DOM 327..335
FT /note="Extracellular"
FT /evidence="ECO:0000255"
FT TRANSMEM 336..356
FT /note="Helical; Name=Segment S6"
FT /evidence="ECO:0000255"
FT TOPO_DOM 357..1196
FT /note="Cytoplasmic"
FT /evidence="ECO:0000255"
FT DOMAIN 383..526
FT /note="RCK N-terminal"
FT REGION 524..544
FT /note="Segment S7"
FT REGION 581..601
FT /note="Segment S8"
FT REGION 645..649
FT /note="Heme-binding motif"
FT REGION 672..697
FT /note="Disordered"
FT /evidence="ECO:0000256|SAM:MobiDB-lite"
FT REGION 748..768
FT /note="Segment S9"
FT REGION 943..963
FT /note="Segment S10"
FT REGION 1098..1149
FT /note="Disordered"
FT /evidence="ECO:0000256|SAM:MobiDB-lite"
FT MOTIF 320..323
FT /note="Selectivity for potassium"
FT MOTIF 914..936
FT /note="Calcium bowl"
FT COMPBIAS 1098..1128
FT /note="Polar residues"
FT /evidence="ECO:0000256|SAM:MobiDB-lite"
FT COMPBIAS 1129..1149
FT /note="Basic and acidic residues"
FT /evidence="ECO:0000256|SAM:MobiDB-lite"
FT BINDING 407
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250"
FT BINDING 430
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250"
FT BINDING 432
FT /ligand="Mg(2+)"
FT /ligand_id="ChEBI:CHEBI:18420"
FT /evidence="ECO:0000250"
FT BINDING 923
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT /evidence="ECO:0000250"
FT BINDING 926
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT /evidence="ECO:0000250"
FT BINDING 929
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT /evidence="ECO:0000250"
FT BINDING 931
FT /ligand="Ca(2+)"
FT /ligand_id="ChEBI:CHEBI:29108"
FT /evidence="ECO:0000250"
FT VAR_SEQ 666
FT /note="L -> LLLTLPCLTALPVFAV (in isoform 2)"
FT /evidence="ECO:0000303|PubMed:12867527"
FT /id="VSP_009992"
FT VAR_SEQ 666
FT /note="L -> LIYSKMSIRKRLIQACCIGCSEIDCSCMSGTLRNNMGTLEQAFPISP
FT VTVNDFSTSLRGF (in isoform 3)"
FT /evidence="ECO:0000303|PubMed:12867527"
FT /id="VSP_009993"
FT VAR_SEQ 666
FT /note="L -> PKMSIRKRLIQACCIGCSEIDCSCMSGTLRNNMGTLEQAFPISPVTV
FT NDFSTSLRGF (in isoform 4)"
FT /evidence="ECO:0000303|PubMed:12867527"
FT /id="VSP_009994"
FT VAR_SEQ 666
FT /note="L -> PAKEEHRLSIHRLSIHSQAAKASYSVTSSKLCTEQQEPVPLVNNRKG
FT SLFLPCDSSLLHLQLLSSSGTGHHTSIKLQRALSLPGKYRYHPNQPILIQKQF (in
FT isoform 5)"
FT /evidence="ECO:0000303|PubMed:12867527"
FT /id="VSP_009995"
SQ SEQUENCE 1196 AA; 134501 MW; AFA212532B571828 CRC64;
MATWNASQII LNSMSNIIES PQSKPRPVMA SNGASLFIPV TMEVPCDQGT RMWWAFLASS
MVTFFGGLFI ILVWRTFKYL WTVCCHCGGK NKEAQKVVNV ASSQVTDGDY KPTDDKEEVG
VAEVGWMTSV KDWAGVMISA QTLTGRVLVV TVFALSIGAL MIYFIDSSNP IESCQNFYKD
FTLQIDMAFN IFFLLYFGLR FIAANDKLWF WLEVNSVVDF FTVPPVFVSV YLNRSWLGLR
FLRALRLIQF SEILQFLNIL KTSNSIKLVN LCSIFISTWL TAAGFIHLVE NSGDPWRNFE
NSQDLSYWEC MYLLMVTMST VGYGDVYAKT TLGRLFMVFF ILGGLAMFAS YVPEIIELIG
NRKKYGGSYS AVSGRKHIVV CGHITLESVS NFLKDFLHKD RDDVNVEIVF LHNISPNLEL
EALFKKHFTQ VEFYQGSVLN PHDLARVKIE SADACLILAN KYCADPDAED ASNIMRVISI
KNYHPKIRII TQMLQYHNKA HLLNIPSWNW KDGDDAICLA ELKLGFIAQS CLAQGLSTML
ANLFSMRSFI KIEEDTWQKY YLEGVANEMY TEYLSSAFVG LSFPAVCELC FVKLKLLMIA
IEYKSEKGES RILINPGNHM KIKEGTLGFF IASDAKEVKR AFFYCKACHD DITDPKRIKK
CACKRLEDEQ PSALSPKKKQ RNGGMRHSPN TSPNMMRHDP LLMTGNDQID NMDSSSVKRY
DSTGMFHWCP AKELDKVLLT RSEAAMTVLS GHVVVCIFGD MTSALIGVRN LVMPLRASNF
HYHELKHIVF VGSLDYIKRE WETLHNFPKV SILPGTPLSR ADLRAVNINL CDMCVILSAN
QNNIDDTSLQ DKECILASLN IKSMQFDDSI GLLQANSQGF TPPGMERSSP DNSPLHGVAR
QASITTGANI PIITELVNDS NVQFLDQDDD DDPDTELYLT QPFACGTAFA VSVLDSLMSA
TYFNDNILTL IRTLVTGGAT PELEALVAEE NALRGGYSTP QTLANRDRCR VAQLALYDGP
FADLGDGGCY GDLYCKALKT YNMLCFGIYR LRDAHISTPS QCTKRYVITN PPYEFELVPT
DLIFCLMQFD HNASQSRASL SHSSHSSHSS SKKSSSVTSI LHTASANRQN RVKARDSRDK
QKMGQAEKKW YTDETENNYP RNIQIKPMST HMANQINQYK STSSLIPPIR EVEDEC
