Growth of large and highly ordered 2D crystals of a K⁺ channel, structural role of lipidic environment.

2D crystallography has proven to be an excellent technique to determine the 3D structure of membrane proteins. Compared to 3D crystallography, it has the advantage of visualizing the protein in an environment closer to the native one. However, producing good 2D crystals is still a challenge and little statistical knowledge can be gained from literature.

Automated screening of 2D crystallization trials using transmission electron microscopy: a high-throughput tool-chain for sample preparation and microscopic analysis.

We have built and extensively tested a tool-chain to prepare and screen two-dimensional crystals of membrane proteins by transmission electron microscopy (TEM) at room temperature. This automated process is an extension of a new procedure described recently that allows membrane protein 2D crystallization in parallel (Iacovache et al., 2010).

The V-antigen of Yersinia forms a distinct structure at the tip of injectisome needles.

Many pathogenic bacteria use injectisomes to deliver effector proteins into host cells through type III secretion. Injectisomes consist of a basal body embedded in the bacterial membranes and a needle. In Yersinia, translocation of effectors requires the YopB and YopD proteins, which form a pore in the target cell membrane, and the LcrV protein, which assists the assembly of the pore.

The role of surfactants in the reversal of active transport mediated by multidrug resistance proteins.

A variety of seven nonionic, one amphoteric and, one anionic surfactant that are applied or investigated as surfactants in drug formulation, were analyzed for their capacity to modulate carrier-mediated transport by efflux pumps. Two cell lines, murine monocytic leukemia cells overexpressing P-glycoprotein (P-gp) and Madin-Darby canine kidney cells stably overexpresssing human multidrug resistance-associated protein 2 (MRP2), were used as test systems. The modulation of P-gp and of MRP2 function was studied by the reversal of rhodamine 123 and of methylfluorescein-glutathione conjugate transport, respectively.

Mechanism of antinociceptive action of clonidine in nonmyelinated nerve fibres.

Despite a large body of clinical evidence in favour of a local anesthetic effect of clonidine, the underlying mechanism has not yet been elucidated. In this study we have used the sucrose-gap method to measure the effects of clonidine on the electrophysiological properties of nonmyelinated nerve fibers in the rabbit vagus nerve. The results showed that clonidine enhanced the hyperpolarizing and reduced the depolarizing afterpotential that follow compound action potentials during electrical activity.