KCNK subunits have two pore-forming P domains and four predicted transmembrane segments. To assess the number of subunits in each pore, we studied external proton block of Kcnk3, a subunit prominent in rodent heart and brain. Consistent with a pore-blocking mechanism, inhibition was dependent on voltage, potassium concentration, and a histidine in the first P domain (P1H). Thus, at pH 6.8 with ...

Membrane voltage controls the passage of ions through voltage-gated K (K(v)) channels, and many studies have demonstrated that this is accomplished by a physical gate located at the cytoplasmic end of the pore. Critical to this determination were the findings that quaternary ammonium ions and certain peptides have access to their internal pore-blocking sites only when the channel gates are open...

A key event in nuclear formation is the assembly of functional nuclear pores. We have used a nuclear reconstitution system derived from Xenopus eggs to examine the process of nuclear pore assembly in vitro. With this system, we have identified three reagents which interfere with nuclear pore assembly, NEM, GTP gamma S, and the Ca++ chelator, BAPTA. These reagents have allowed us to determine th...

Aldol condensation of n -pentanal can lead to pore blocking and hence transport limitations in supported liquid phase (SLP) catalysts. By careful texture optimization this effect be minimized.

L. Dahil, Istanbul Arel University, Department of Mechanical and Metal Technologies, Turkey, A. Karabulut, Afyon Kocatepe University, Faculty of Technology, MechanicalEngineering, Turkey, S. Baspınar, Afyon Kocatepe University, Technical EducationFaculty, Turkey In this study,damping ratios of 3 samples made of aluminum foam material, which have diff erent-density pores, were calculated, the ef...

Multilayer diffusion and capillary condensation of propylene on supported y-alumina films greatly improved the permeability and selectivity. Multilayer diffusion, occurring at relative pressures of 0.4 to 0.8 strongly increased the permeability to 6 times the Knudsen permeability, yielding permeabilities of 3.2 x 10m5 mol/m’-see-Pa. The occurrence of a maximum in the permeability coincides with...

The activity of single L-type Ca2+ channels was recorded from cell-attached patches on acutely isolated skeletal muscle fibers from the mouse. The experiments were concerned with the mechanism by which aminoglycoside antibiotics inhibit ion flow through the channel. Aminoglycosides produced discrete fluctuations in the single-channel current when added to the external solution. The blocking kin...

Venoms from various predatory species, such as fish hunting molluscs scorpions, snakes and arachnids contain a large spectrum of toxins that include blockers of voltage-gated calcium channels. These peptide blockers act by two principal manners - physical occlusion of the pore and prevention of activation gating. Many of the calcium channel-blocking peptides have evolved to tightly occupy their...