| Literature References | 1. MILLER, C.
An overview of the potassium channel family.
GENOME BIOL. 1(4) 1-5 (2000).
2. CONLEY, E.C. AND BRAMMAR, W.J.
MinK.
IN THE ION CHANNEL FACTSBOOK, VOLUME IV, ACADEMIC PRESS, 1999, PP.703-767.
3. PICCINI, M., VITELLI, F., SERI, M., GALIETTA, L.J.V., MORAN, O., BULFONE,
A., BANFI, S., POBER, B. AND RENIERI, A.
KCNE1-like gene is deleted in AMME contigious gene syndrome: identification
and characterization of the human and mouse homologs.
GENOMICS 60 251-257 (1999).
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| 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].
Some types of K+ channel are closed at the resting potential of the cell,
but open on membrane depolarisation, and are thus known as voltage-gated
channels. Each of these types of channel typically comprises 4 pore-forming
alpha subunits that may associate with one of a number of different types of
beta subunit. Two types of beta subunit (KCNE and KCNAB) are presently known
to associate with voltage-gated alpha subunits (Kv, KCNQ and eag-like).
However, not all combinations of alpha and beta subunits are possible.
The KCNE family of K+ channel subunits are membrane glycoproteins that
possess a single transmembrane (TM) domain. They share no structural
relationship with the alpha subunit proteins, which possess pore forming
domains. The subunits appear to have a regulatory function, modulating the
kinetics and voltage dependence of the alpha subunits of voltage-dependent
K+ channels [2]. KCNE subunits are formed from short polypeptides of ~130
amino acids, and are divided into five subfamilies: KCNE1 (MinK/IsK),
KCNE2 (MiRP1), KCNE3 (MiRP2), KCNE4 (MiRP3) and KCNE1L (AMMECR2).
KCNE1 subunits associate with KCNQ1 alpha subunits to form channels that
are responsible for the IkS currents that determine the duration of the
action potential in cardiac muscle. Mutations in both of the genes encoding
these subunits cause an inherited disorder that increases the risk of death
from cardiac arrhythmia (long QT syndrome type 1) and Jervell and
Lange-Nielsen syndrome, associated with congenital deafness [3].
KCNE1CHANNEL is a 4-element fingerprint that provides a signature for the
KCNE voltage-gated K+ channel beta-1 subunit. The fingerprint was derived
from an initial alignment of 7 sequences: the motifs were drawn from
conserved regions spanning the N- and C-terminal portions of the alignment,
focusing on those sections that characterise the KCNE1 subunits but
distinguish them from the rest of the KCNE family - motifs 1 and 2 lie
in the extracellular N-terminus; and motifs 3 and 4 lie in the cytoplasmic
C-terminus. A single iteration on SPTR39.22_17.3f was required to reach
convergence, no further sequences being identified beyond the starting set.
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