Ions bound near the external mouth of the potassium channel pore impede the C-type inactivation conformational change (Lopez-Barneo, J., T. Hoshi, S. Heinemann, and R. Aldrich. 1993. Receptors Channels. 1:61- 71; Baukrowitz, T., and G. Yellen. 1995. Neuron. 15:951-960). In this study, we present evidence that the occupancy of the C-type inactivation modulatory site by permeant ions is not solel...

Nup98 is a component of the nuclear pore that plays its primary role in the export of RNAs. Nup98 is expressed in two forms, derived from alternate mRNA splicing. Both forms are processed into two peptides through autoproteolysis mediated by the C-terminal domain of hNup98. The three-dimensional structure of the C-terminal domain reveals a novel protein fold, and thus a new class of autocatalyt...

Essential to nerve and muscle function, little is known about how potassium leak channels operate. KCNKØ opens and closes in a kinase-dependent fashion. Here, the transition is shown to correspond to changes in the outer aspect of the ion conduction pore. Voltage-gated potassium (VGK) channels open and close via an internal gate; however, they also have an outer pore gate that produces "C-type"...

Cementation factor is a critical parameter, which affects water saturation calculation. In carbonate rocks, due to the sensitivity of this parameter to pore type, water saturation estimation has associated with high inaccuracy. Hence developing a reliable mathematical strategy to determine these properties accurately is of crucial importance. To this end, genetic algorithm pattern search is emp...

The final step of the intracellular life cycle of Legionella pneumophila and other intracellular pathogens is their egress from the host cell after termination of intracellular replication. We have previously isolated five spontaneous mutants of L. pneumophila that replicate intracellularly similar to the wild-type strain but are defective in pore formation-mediated cytolysis and egress from ma...

In tight junctions, both claudin-2 and claudin-10b form paracellular cation-selective pores by the interaction of the first ECL 1 with permeating ions. We hypothesized that a highly conserved aromatic residue near the pore selectivity filter of claudins contributes to cation selectivity by cation-π interaction with the permeating cation. To test this, we generated MDCK I Tet-off cells stably tr...

Bacterial cells avoid lysis in response to hypoosmotic shock through the opening of the mechanosensitive channel MscL. Upon channel opening, MscL is thought to expand in the plane of the membrane and form a large pore with an estimated diameter of 3-4 nm. Here, we set out to analyze the closed and open structure of cell-free MscL. To this end, we characterized the function and structure of wild...

Ca(2+)-dependent regulation of fusion pore dilation and closure is a key mechanism determining the output of cellular secretion. We have recently described 'fusion-activated' Ca(2+) entry (FACE) following exocytosis of lamellar bodies in alveolar type II cells. FACE regulates fusion pore expansion and facilitates secretion. However, the mechanisms linking this locally restricted Ca(2+) signal a...

X-ray structures permit theoretical study of Cl(-) permeation along bacterial ClC Cl(-) pores. We determined the lowest energy curvilinear pathway, identified anion-coordinating amino acids, and calculated the electrostatic potential energy profiles. We find that all four bacterial ClC Cl(-) crystal structures correspond to closed states. E148 and S107 side chains form steric barriers on both s...