Cholesterol is the major sterol component of all mammalian cell plasma membranes and plays a critical role in cell function and growth. Previous studies have shown that cholesterol inhibits inward rectifier K(+) (Kir) channels, but have not distinguished whether this is due directly to protein-sterol interactions or indirectly to changes in the physical properties of the lipid bilayer. Using pu...

Rat and human cDNAs were isolated that both encoded a 360 amino acid polypeptide with a tertiary structure typical of inwardly rectifying K+ channel (Kir) subunits. The new proteins, termed Kir7.1, were <37% identical to other Kir subunits and showed various unique residues at conserved sites, particularly near the pore region. High levels of Kir7.1 transcripts were detected in rat brain, lung,...

OBJECTIVE We investigated the effects of angiotensin II (Ang II) on inward rectifier K+ (Kir) channels in small-diameter coronary arterial smooth muscle cells (SCASMCs) of control and isoproterenol (Iso)-induced hypertrophied rabbits. METHODS AND RESULTS Kir current amplitude and Kir channel protein expression were definitely lower in the Iso-induced hypertrophied model than in the control. I...

Strongly inwardly rectifying potassium channels of the Kir 2 subfamily (IRK1, IRK2, and IRK3) are involved in maintenance and modulation of cell excitability in brain and heart. Electrophysiological studies of channels expressed in heterologous systems have suggested that the pore-conducting pathway contains four subunits. However, inferences from electrophysiological studies have not been test...

Ion channels establish and regulate membrane potentials in excitable and non-excitable cells. How functional diversification of ion channels contributed to the evolution of nervous systems may be understood by studying organisms at key positions in the evolution of animal multicellularity. We have carried out the first analysis of ion channels cloned from a marine sponge, Amphimedon queenslandi...

Inwardly rectifying K+ channel subunits may form homomeric or heteromeric channels with distinct functional properties. Hyperpolarizing commands delivered to Xenopus oocytes expressing homomeric Kir 4.1 channels evoke inwardly rectifying K+ currents which activate rapidly and undergo a pronounced decay at more hyperpolarized potentials. In addition, Kir 4.1 subunits form heteromeric channels wh...

The etiology of common idiopathic epileptic syndromes is genetically determined, but the complex pattern of inheritance suggests an epistatic interaction of several susceptibility genes. Mutations in over 70 genes now define biological pathways leading to rare monogenic forms of epilepsy in humans and animals. Recognizing the molecular basis of an ion-channel disease has provided new opportunit...

Potassium channels vary in their function and regulation, yet they maintain a number of important features - they are involved in the control of potassium flow, cell volume, cell membrane resting potential, cell excitability and hormone release. The potassium (K(+)) inward rectifier (Kir) superfamily of channels are potassium selective channels, that are sensitive to the concentration of K(+) i...

K(+) channels fulfill roles spanning from the control of excitability to the regulation of transepithelial transport. Here we review two groups of K(+) channels, pH-regulated K2P channels and the transport group of Kir channels. After considering advances in the molecular aspects of their gating based on structural and functional studies, we examine their participation in certain chosen physiol...