ID KCMA1_CANFA STANDARD; PRT; 1159 AA.
DT 05-JUL-2004 (Rel. 44, Created)
DT 05-JUL-2004 (Rel. 44, Last sequence update)
DT 13-SEP-2005 (Rel. 48, Last annotation update)
DE Calcium-activated potassium channel alpha subunit 1 (Calcium-activated
DE potassium channel, subfamily M, alpha subunit 1) (Maxi K channel)
DE (MaxiK) (BK channel) (K(VCA)alpha) (BKCA alpha) (KCa1.1) (Slowpoke
DE homolog) (Slo homolog) (Slo-alpha) (Slo1) (Fragment).
GN Name=KCNMA1; Synonyms=KCNMA;
OS Canis familiaris (Dog).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC Mammalia; Eutheria; Laurasiatheria; Carnivora; Fissipedia; Canidae;
RP NUCLEOTIDE SEQUENCE, FUNCTION, AND TISSUE SPECIFICITY.
RC TISSUE=Colon smooth muscle;
RX PubMed=8897882 [NCBI, ExPASy, EBI, Israel, Japan];
RA Vogalis F., Vincent T., Qureshi I., Schmalz F.M., Ward M.W.,
RA Sanders K.M., Horowitz B.;
RT "Cloning and expression of the large-conductance Ca(2+)-activated K+
RT channel from colonic smooth muscle.";
RL Am. J. Physiol. 271:G629-G639(1996).
CC -!- FUNCTION: Potassium channel activated by both membrane
CC depolarization or increase in cytosolic Ca(2+) that mediates
CC export of K(+). It is also activated by the concentration of
CC cytosolic Mg(2+). Its activation dampens the excitatory events
CC that elevate the cytosolic Ca(2+) concentration and/or depolarize
CC the cell membrane. It therefore contributes to repolarization of
CC the membrane potential. Plays a key role in controlling
CC excitability in a number of systems, such as regulation of the
CC contraction of smooth muscle, the tuning of hair cells in the
CC cochlea, regulation of transmitter release, and innate immunity.
CC In smooth muscles, its activation by high level of Ca(2+), caused
CC 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
CC hair cell and thereby helps to establish a tonotopic map. Kinetics
CC of KCNMA1 channels are determined by alternative splicing,
CC phosphorylation status and its combination with modulating beta
CC subunits. Highly sensitive to both iberiotoxin (IbTx) and
CC charybdotoxin (CTX) (By similarity).
CC -!- SUBUNIT: Homotetramer; which constitutes the calcium-activated
CC potassium channel. Interacts with beta subunits KCNMB1, KCNMB2,
CC KCNMB3 and KCNMB4. Beta subunits are accessory, and modulate its
CC activity (By similarity).
CC -!- SUBCELLULAR LOCATION: Integral membrane protein (By similarity).
CC -!- ALTERNATIVE PRODUCTS:
CC Event=Alternative splicing; Named isoforms=1;
CC Comment=May be partially controlled by hormonal stress. A number
CC of isoforms are produced;
CC IsoId=Q28265-1; Sequence=Displayed;
CC -!- TISSUE SPECIFICITY: Expressed in all vascular and smooth muscles.
CC -!- DOMAIN: The S0 segment is essential for the modulation by the
CC accessory beta subunits KCNMB1, KCNMB2, KCNMB3 and KCNMB4 (By
CC -!- DOMAIN: The S4 segment, which is characterized by a series of
CC positively charged amino acids at every third position, is part of
CC the voltage-sensor (By similarity).
CC -!- DOMAIN: The pore-forming domain (also referred as P region) is
CC imbedded into the membrane, and forms the selectivity filter of
CC the pore. It contains the signature sequence of potassium channels
CC that displays selectivity to potassium (By similarity).
CC -!- DOMAIN: The BK-T1 domain mediates the homotetramerization, thereby
CC promoting the assembly of monomers into functional potassium
CC channel. It includes the RCK domain, which contains binding sites
CC for Ca(2+) and Mg(2+) (By similarity).
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
CC Ca(2+) sensors regions required for activation of the channel (By
CC -!- PTM: Phosphorylated (Probable). Phosphorylation by kinases such as
CC PKA and/or PKG. In smooth muscles, phosphorylation affects its
CC activity (By similarity).
CC -!- MISCELLANEOUS: The protein was initially thought to contain two
CC functionally distinct parts: The core channel (from the N-terminus
CC to the S9 segment) that mediates the channel activity, and the
CC cytoplasmic tail (from the S9 segment to the C-terminus) that
CC mediates the calcium sensing. The situation is however more
CC complex, since the core channel contains binding sites for Ca(2+)
CC and Mg(2+).
CC -!- SIMILARITY: Belongs to the potassium channel family. Calcium-
CC activated subfamily.
CC -!- SIMILARITY: Contains 1 BK-T1 domain.
CC This Swiss-Prot entry is copyright. It is produced through a collaboration
CC between the Swiss Institute of Bioinformatics and the EMBL outstation -
CC the European Bioinformatics Institute. There are no restrictions on its
CC use as long as its content is in no way modified and this statement is not
DR EMBL; U41001; AAA84000.1; -; mRNA. [EMBL / GenBank / DDBJ] [CoDingSequence]
DR HSSP; O27564; 1LNQ. [HSSP ENTRY / SWISS-3DIMAGE / PDB]
DR Ensembl; ENSCAFG00000015465; Canis_familiaris
DR InterPro; IPR003929; BK_channel_alpha.
DR InterPro; IPR005821; Ion_trans.
DR InterPro; IPR001622; K+channel_pore.
DR InterPro; IPR005820; M+channel_nlg.
DR InterPro; Graphical view of domain structure.
DR Pfam; PF03493; BK_channel_a; 1.
DR Pfam; PF00520; Ion_trans; 1.
DR Pfam; Graphical view of domain structure.
DR PRINTS; PR01449; BKCHANNELA.
DR HOVERGEN [Family / Alignment / Tree]
DR BLOCKS; Q28265.
DR ProtoNet; Q28265.
DR ProtoMap; Q28265.
DR PRESAGE; Q28265.
DR DIP; Q28265.
DR ModBase; Q28265.
DR SWISS-2DPAGE; GET REGION ON 2D PAGE.
KW Alternative splicing; Calcium; Ion transport; Ionic channel;
KW Magnesium; Metal-binding; Phosphorylation; Potassium;
KW Potassium channel; Potassium transport; Transmembrane; Transport;
KW Voltage-gated channel.
FT TOPO_DOM <1 24 Extracellular (Potential).
FT TRANSMEM 25 45 Segment S0 (Potential).
FT TOPO_DOM 46 116 Cytoplasmic (Potential).
FT TRANSMEM 117 137 Segment S1 (Potential).
FT TOPO_DOM 138 152 Extracellular (Potential).
FT TRANSMEM 153 173 Segment S2 (Potential).
FT TOPO_DOM 174 177 Cytoplasmic (Potential).
FT TRANSMEM 178 198 Segment S3 (Potential).
FT TOPO_DOM 199 202 Extracellular (Potential).
FT TRANSMEM 203 223 Segment S4 (Potential).
FT TOPO_DOM 224 238 Cytoplasmic (Potential).
FT TRANSMEM 239 259 Segment S5 (Potential).
FT TRANSMEM 306 326 Segment S6 (Potential).
FT TOPO_DOM 327 1159 Cytoplasmic (Potential).
FT DOMAIN 327 493 BK-T1.
FT REGION 274 296 Pore-forming, in membrane (Potential).
FT REGION 341 430 RCK.
FT REGION 494 514 Segment S7.
FT REGION 551 571 Segment S8.
FT REGION 717 737 Segment S9.
FT REGION 912 932 Segment S10.
FT MOTIF 290 293 Selectivity for potassium.
FT MOTIF 883 905 Calcium bowl.
FT METAL 377 377 Magnesium (By similarity).
FT METAL 400 400 Magnesium (By similarity).
FT METAL 402 402 Magnesium (By similarity).
FT MOD_RES 643 643 Phosphothreonine (By similarity).
FT MOD_RES 645 645 Phosphoserine (By similarity).
FT MOD_RES 857 857 Phosphoserine (By similarity).
FT MOD_RES 858 858 Phosphoserine (By similarity).
FT NON_TER 1 1
SQ SEQUENCE 1159 AA; 130296 MW; D8CF38C32971BB64 CRC64;
EPNMDALIIP VTMEVPCDSR GQRMWWAFLA SSMVTFFGGL FIILLWRTLK YLWTVCCHCG
DKTKEAQKIN NGSSQADGTL KPVDEKEEAV AAEVGWMTSV KDWAGVMISA QTLTGRVLVV
LVFALSIGAL VIYFIDSSNP IESCQNFYKD FTLQIDMAFN VFFLLYFGLR FIAANDNLWF
WLEVNSVVDF FTVPPVFVSV YLNRSWLGLR FLRALRLIQF SEILQFLNIL KTSNSIKLVN
LLSIFISTWL TAAGFIHLVE NSGDPWENFQ NSQALTYWEC VYLLMVTMST VGYGDVYAKT
TPGGLFIVFF ILGGLAMFAS YVPEIIEIIG NRKKYGGSYS AVSGRKHIVV CGHITLESVS
HFLKDFLHKD RDDVNVEIVF LHNISPNLEL EALFKRHFTQ VEFYQGSVLN PHDLARVKIE
SADACLILAN KYCDDPDAED ASNIMRVISI KNYHPKIRII TQMLQYHNKA HLLNIPSWNW
KEGDDAICLA ELRLGFIAQS CLAQGLSTML ANLFSIGSFI KIEEDTWHKY YLEGVSNEMY
TEYLSSAFVG LSFPTVCELC FVKLKLLMIA IEYKSANRES RILINPGNHL KIQEGTSGFF
IASDAKEVKR AFFYCKACHN DITDPKRIKK CGCKRLEDEQ PSTLSPKKKQ RNGGMRNSPS
SSPKLMRHDP LLIPGNDQID NMDSNVKKYD STGMFHWCAP KEIEKVISTR SEAAMTVLSG
HVVVCIFGHV SSALIGLRNL VMPLRASNFH YHELKHIVFV GSIEYLKREW ETLHNFPKVS
ILPGTPLTRA DLRAVNINLC DMCVILSANQ NNIDDTSLQD KECILASLNI KSMQFDDSIG
VLQANSQGFT PPGMDKSSPD NSPVHGMLRQ PSITTGVNIP IITELVNDTN VQFLDQDDDD
DPDTELYLTQ PFACGTAFAV SVLDSLMSAT YFNDNILTLI RTLVTGGATP ELEALIAEEN
ALRGGYSTPQ TLANRDRCRV AQLALLDGPF ADLGDGGCYG DLFCKALKTY NMLCFGIYRL
RDAHLSTPSQ CTKRYVITNP PYRFELVPTD LIFCLMQFDH NAGQSRASLS HSSHSSQSSS
KKSSSVHSIP STANRQNRPK SRESRDKQTE KKWFTDEPDN AYPRNIQIEP MSTHMANQIN