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PR01462

Identifier
KCNQ3CHANNEL  [View Relations]  [View Alignment]  
Accession
PR01462
No. of Motifs
9
Creation Date
14-NOV-2000
Title
KCNQ3 voltage-gated potassium channel signature
Database References
PRINTS; PR00169 KCHANNEL; PR01459 KCNQCHANNEL
Literature References
1. MILLER, C. 
An overview of the potassium channel family.
GENOME BIOL. 1(4) 1-5 (2000). 
 
2. ASHCROFT, F.M. 
Voltage-gated K+ channels.
IN ION CHANNELS AND DISEASE, ACADEMIC PRESS, 2000, PP.111-116.
 
3. SANGUINETTI, M. C.
Maximal function of minimal K+ channel subunits.
TRENDS PHARMACOL.SCI. 21 199-201 (2000).
 
4. WANG Q., CURRAN, M.E., SPLAWSKI, I., BURN, T.C., MILLHOLLAND, J.M.,
VANRAAY, T.J., SHEN, J., TIMOTHY, K.W., VINCENT, G.M., DE JAGER, T.,
SCHWARTZ, P.J., TOUBIN, J.A., MOSS, A.J., ATKINSON, D.L., LANDES, G.M.,
CONNORS, T.D. AND KEATING, M.T. 
Positional cloning of a novel potassium channel gene: KVLQT1 mutations
cause cardiac arrhythmias.
NAT.GENET. 12(1) 17-23 (1996).
 
5. BIERVERT, C., SCHROEDER, B.C., KUBISCH, C., BERKOVIC, S.F., PROPPING, P.,
JENTSCH, T.J. AND STEINLEIN, O.K.
A potassium channel mutation in neonatal human epilepsy.
SCIENCE 279 403-406 (1998).
 
6. SCHROEDER, B.C., KUBISCH, C., STEIN, V. AND JENTSCH, T.J.
Moderate loss of function of cyclic-AMP-modulated KCNQ2/KCNQ3 K+ channels
causes epilepsy.
NATURE 396 687-690 (1998).

Documentation
Potassium ion (K+) channels are a structurally diverse group of proteins
that facilitate the flow of K+ ions across cell membranes. They are
ubiquitous, being present in virtually all cell types. Activation of K+
channels tends to hyperpolarise cells, reducing the membrane's electrical
resistance, dampening nervous activity. In eukaryotic cells, K+ channels
are involved in neural signalling and generation of the cardiac rhythm, and
act as effectors in signal transduction pathways involving G protein-
coupled receptors (GPCRs). In prokaryotic cells, they play a role in the
maintenance of ionic homeostasis [1].
 
Structurally, KCNQ channels belong to the subfamily of K+ channels whose
subunits contain 6 transmembrane (TM) domains: these are the voltage-gated
K+ channels, the KCNQ channels, the EAG-like K+ channels and 3 kinds of 
Ca2+-activated K+ channel (BK, IK and SK) [2]. All K+ channels share a
characteristic sequence feature: a TMxTVGYG motif that resides between
the 2 C-terminal membrane-spanning helices, and forms the K+-selective 
pore domain [1].
 
KCNQ channels differ from other voltage-gated 6 TM helix channels, chiefly 
in that they possess no tetramerisation domain. Consequently, they rely on
interaction with accessory subunits, or form heterotetramers with other
members of the family [3]. Currently, 5 members of the KCNQ family are 
known. These have been found to be widely distributed within the body,
having been shown to be expressed in the heart, brain, pancreas, lung,
placenta and ear. They were initially cloned as a result of a search for 
proteins involved in cardiac arhythmia. Subsequently, mutations in other 
KCNQ family members have been shown to be responsible for some forms of
hereditary deafness [4] and benign familial neotnatal epilepsy [5].
 
The KCNQ3 channel subunit is thought to form active channels by hetero-
tetramerisation with KCNQ2, although some K+ channel activity does result
from the expression of KCNQ3 alone [6]. Channel function is modulated by
phosphorylation; experiments have demonstrated that an increase in
intracellular cAMP concentration can enhance channel activity [2].
Frameshift mutations in both KCNQ2 and KCNQ3 are associated with benign
familial neonatal epilepsy [6], a disorder in which infants suffer
convulsions within the first 3 days of life. These symptoms usually
disappear after about 3 months, but affected individuals have a higher
than average chance of subsequently developing epilepsy (10-15%) in later
life [5].
 
KCNQ3CHANNEL is a 9-element fingerprint that provides a signature for the
KCNQ3 voltage-gated potassium channel subtype. The fingerprint was derived
from an initial alignment of 3 sequences: the motifs were drawn from 
conserved regions spanning virtually the full alignment length, focusing
on those sections that characterise the KCNQ3 channel but distinguish it
from other members of the K+ channel superfamily - motif 1 lies within the
N-terminal intracellular region; motif 2 encodes the putative extracellular
loop between TM domains 1 and 2; motif 3 spans the C-terminal half of 
putative TM domain 3; motif 4 encodes the putative cytoplasmic loop between
TM domains 4 and 5; and motifs 5-9 reside within the C-terminal intra-
cellular region. A single iteration on SPTR39_14f was required to reach 
convergence, no further sequences being identified beyond the starting set.
Summary Information
3 codes involving  9 elements
0 codes involving 8 elements
0 codes involving 7 elements
0 codes involving 6 elements
0 codes involving 5 elements
0 codes involving 4 elements
0 codes involving 3 elements
0 codes involving 2 elements
Composite Feature Index
9333333333
8000000000
7000000000
6000000000
5000000000
4000000000
3000000000
2000000000
123456789
True Positives
CIQ3_HUMAN    O88944        Q9Z240        
Sequence Titles
CIQ3_HUMAN  VOLTAGE-GATED POTASSIUM CHANNEL PROTEIN KQT-LIKE 3 - Homo sapiens (Human). 
O88944 POTASSIUM CHANNEL - Rattus norvegicus (Rat).
Q9Z240 POTASSIUM CHANNEL - Rattus norvegicus (Rat).
Scan History
SPTR39_14f 1  50   NSINGLE    
Initial Motifs
Motif 1  width=14
Element Seqn Id St Int Rpt
QGIGLLAKTPLSRP O88944 84 84 -
QGIGLLAKTPLSRP Q9Z240 46 46 -
QGIGLLAKTPLSRP CIQ3_HUMAN 83 83 -

Motif 2 width=12
Element Seqn Id St Int Rpt
LGCLILAVLTTF O88944 135 37 -
LGCLILAVLTTF Q9Z240 97 37 -
LGCLILAVLTTF CIQ3_HUMAN 134 37 -

Motif 3 width=10
Element Seqn Id St Int Rpt
SVPVVAVGNQ O88944 210 63 -
SVPVVAVGNQ Q9Z240 172 63 -
SVPVVAVGNQ CIQ3_HUMAN 209 63 -

Motif 4 width=14
Element Seqn Id St Int Rpt
VPEMDAQGEEMKEE O88944 287 67 -
VPEMDAQGEEMKEE Q9Z240 249 67 -
VPEVDAQGEEMKEE CIQ3_HUMAN 286 67 -

Motif 5 width=13
Element Seqn Id St Int Rpt
PVGLNNKERFRTA O88944 464 163 -
PVGLNNKERFRTA Q9Z240 426 163 -
PVGLNNKERFRTA CIQ3_HUMAN 463 163 -

Motif 6 width=18
Element Seqn Id St Int Rpt
PSTPKHKKSQKGSAFTYP O88944 578 101 -
PSTPKHKKSQKGSAFTYP Q9Z240 540 101 -
PSTPKHKKSQKGSAFTFP CIQ3_HUMAN 577 101 -

Motif 7 width=20
Element Seqn Id St Int Rpt
TIICNYSESGPPDPPYSFHQ O88944 683 87 -
TIICNYSESGPPDPPYSFHQ Q9Z240 645 87 -
TIICNYSETGPPEPPYSFHQ CIQ3_HUMAN 682 87 -

Motif 8 width=17
Element Seqn Id St Int Rpt
KAQANLPSSGSTYAERP O88944 730 27 -
KAQANLPSSGSTYAERP Q9Z240 692 27 -
KVQATPPSSATTYVERP CIQ3_HUMAN 729 27 -

Motif 9 width=16
Element Seqn Id St Int Rpt
DSCVSYHSQTELQGPY O88944 756 9 -
DSCVSYHSQTELQGPY Q9Z240 718 9 -
DSRVSCHSQADLQGPY CIQ3_HUMAN 755 9 -
Final Motifs
Motif 1  width=14
Element Seqn Id St Int Rpt
QGIGLLAKTPLSRP O88944 84 84 -
QGIGLLAKTPLSRP Q9Z240 46 46 -
QGIGLLAKTPLSRP CIQ3_HUMAN 83 83 -

Motif 2 width=12
Element Seqn Id St Int Rpt
LGCLILAVLTTF O88944 135 37 -
LGCLILAVLTTF Q9Z240 97 37 -
LGCLILAVLTTF CIQ3_HUMAN 134 37 -

Motif 3 width=10
Element Seqn Id St Int Rpt
SVPVVAVGNQ O88944 210 63 -
SVPVVAVGNQ Q9Z240 172 63 -
SVPVVAVGNQ CIQ3_HUMAN 209 63 -

Motif 4 width=14
Element Seqn Id St Int Rpt
VPEMDAQGEEMKEE O88944 287 67 -
VPEMDAQGEEMKEE Q9Z240 249 67 -
VPEVDAQGEEMKEE CIQ3_HUMAN 286 67 -

Motif 5 width=13
Element Seqn Id St Int Rpt
PVGLNNKERFRTA O88944 464 163 -
PVGLNNKERFRTA Q9Z240 426 163 -
PVGLNNKERFRTA CIQ3_HUMAN 463 163 -

Motif 6 width=18
Element Seqn Id St Int Rpt
PSTPKHKKSQKGSAFTYP O88944 578 101 -
PSTPKHKKSQKGSAFTYP Q9Z240 540 101 -
PSTPKHKKSQKGSAFTFP CIQ3_HUMAN 577 101 -

Motif 7 width=20
Element Seqn Id St Int Rpt
TIICNYSESGPPDPPYSFHQ O88944 683 87 -
TIICNYSESGPPDPPYSFHQ Q9Z240 645 87 -
TIICNYSETGPPEPPYSFHQ CIQ3_HUMAN 682 87 -

Motif 8 width=17
Element Seqn Id St Int Rpt
KAQANLPSSGSTYAERP O88944 730 27 -
KAQANLPSSGSTYAERP Q9Z240 692 27 -
KVQATPPSSATTYVERP CIQ3_HUMAN 729 27 -

Motif 9 width=16
Element Seqn Id St Int Rpt
DSCVSYHSQTELQGPY O88944 756 9 -
DSCVSYHSQTELQGPY Q9Z240 718 9 -
DSRVSCHSQADLQGPY CIQ3_HUMAN 755 9 -