Humanether a` go-go potassium channels (hEAG1) open in response to
membrane depolarization and they are inhibited by Ca
(CaM), presumably binding to the C-terminal domain of the channel sub-units. Deletion of the cytosolic N-terminal domain resulted in complete
abolition of Ca
⁄CaM sensitivity suggesting the existence of further CaM
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học General Psychiatry cung cấp cho các bạn kiến thức về ngành y đề tài: Expression of K2P5.1 potassium channels on CD4+ T lymphocytes correlates with disease activity in rheumatoid arthritis patients...
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: " Pulmonary vasoconstrictor action of KCNQ potassium channel blockers...
Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: " Hypoxic pulmonary vasoconstriction: role of voltage-gated potassium channels...
) is the most abundant inorganic cation in plant cells.
Unlike animals, plants lack sodium⁄potassium exchangers. Instead, plant
cells have developed unique transport systems for K
Besides being activated by G-proteinb⁄c subunits, G-protein activated
potassium channels (GIRKs) are regulated by cAMP-dependent protein
kinase. Back-phosphorylation experiments have revealed that the GIRK1
subunit is phosphorylatedin vivo upon protein kinase A activation inXeno-pusoocytes, whereas phosphorylation was eliminated when protein kinase
A was blocked.
The prokaryotic potassium channel fromStreptomyces lividans, KcsA, is
the first channel that has a known crystal structure of the transmembrane
domain. The crystal structure of its soluble C-terminal domain, however,
still remains elusive.
Functional diversity of potassium channels in both prokaryotic and euk-aryotic cells suggests multiple levels of regulation. Posttranslational regula-tion includes differential subunit assembly of homologous pore-forming
subunits. In addition, a variety of modulatory subunits may interact with
the pore complex either statically or dynamically. Kv2.1 is a delayed recti-fier potassium channel isolated by expression cloning.
Protein–protein interactions are critical for protein trafficking, localization
and the regulation of ion channels. Thehuman ether-a-go-go-related gene
(herg) encodes the a-subunit of the potassium channel underlying the rapid
component of the cardiac delayed rectifier current.
Hemitoxin (HTX) is a new K
channel blocker isolated from the venom
of the Iranian scorpionHemiscorpius lepturus. It represents only 0.1% of
the venom proteins, and displaces [
I]a-dendrotoxin from its site on rat
brain synaptosomes with an IC50value of 16 nm.
KcsA, a potassium channel fromStreptomyces lividans, was the first ion
channel to have its transmembrane domain structure determined by crystal-lography. Previously we have shown that its C-terminal cytoplasmic
domain is crucial for the thermostability and the expression of the channel.
Expression was almost abolished in its absence, but could be rescued by
the presence of an artificial left-handed coiled coil tetramerization domain
Pannexin 1 (Panx1), a member of the second gap junction protein family
identified in vertebrates, appears to preferentially form non-junctional
membrane channels. A candidate regulatory protein of Panx1 is the potas-sium channel subunit Kvb3, previously identified by bacterial two-hybrid
The voltage-gated potassium channel Kv4.3 was coexpressed with itsb-sub-unit Kv channel-interacting protein 2 and the angiotensin type 1 receptor in
HEK-293 cells. Proteomic analysis of proteins coimmunoprecipitated with
Kv4.3 revealed that Kv4.3 is associated with Rap guanine nucleotide
exchange factors MR-GEF and EPAC-1.
Unusually among ATP-binding cassette proteins, the sulfonylurea receptor
(SUR) acts as a channel regulator. ATP-sensitive potassium channels are
octameric complexes composed of four pore-forming Kir6.2 subunits and
four regulatory SUR subunits. Two different genes encode SUR1 (ABCC8)
and SUR2 (ABCC9), with the latter being differentially spliced to give
SUR2A and SUR2B, which differ only in their C-terminal 42 amino acids.
Neuronal cell-surface antigens can be the target of antibodies in some patients with paraneoplastic encephalitis. A few of these antigens have been identified, including the NR1/NR2 subunits of NMDA receptors (Fig. 97-1) and voltage-gated potassium channels (VGKC). These disorders are more responsive to immunotherapy than those associated with immune responses to intracellular antigens.
Antibodies to NR1/NR2 subunits of the NMDA receptor in a patient with paraneoplastic encephalitis and ovarian teratoma.
What is ‘biochemical pharmacology’?
• A fancy way of saying ‘pharmacology’, and of hiding
the fact that we are sneaking a subject of medical interest
into the UW biochemistry curriculum.
• An indication that we are not going to discuss prescriptions
for your grandmother’s aching knee; we will focus
on the scientific side of things but not on whether to take
the small blue pill before or after the meal.
What is it not?
• A claim that we accurately understand the mechanism
of action of each practically useful drug in biochemical
Potassium channel tetramerization domain (KCTD) proteins contain a
bric-a-brac, tramtrak and broad complex (BTB) domain that is most simi-lar to the tetramerization domain (T1) of voltage-gated potassium chan-nels.
release from Ca
stores is a ‘quantal’ process; it terminates after a
rapid release of stored Ca
. To explain the quantal nature, it has been
supposed that a decrease in luminal Ca
acts as a ‘brake’ on store release.
However, the mechanism for the attenuation of Ca
The novel sex-specific potassium channel inhibitor IsTX, a
41-residue peptide, was isolated from the venom of male
techniques revealed that the structure of IsTX contains a
cysteine-stabilizeda/b-fold. IsTX is classified, based on its
sequential and structural similarity, in the scorpion short
toxin familya-KTx6. Thea-KTx6 family contains a single
a-helix and twob-strands connected by four disulfide brid-ges and binds to voltage-gated K
channels and apamin-sensitive Ca