Membrane trafficking from endosomes to the trans-Golgi network or the plasma membrane is driven by the retromer complex. Through structural analysis of the cargo-bound complex, Lucas et al. describe a mechanism by which endosomal membrane recruitment and cargo recognition are integrated through cooperative interactions between retromer subunits.

The kinetics of K(+)-leucine cotransport in the midgut of lepidopteran larvae was investigated using brush border membrane vesicles. Initial rate (3 s) of leucine uptake was determined under experimental conditions similar to those occurring in vivo, i.e. in the presence of delta psi much greater than 0 (inside negative) and a delta pH of 1.4 units (7.4in/8.8out). Leucine and K+ bind to the car...

beta-Galactoside alpha 2,6-sialyltransferase (ST) is a type II integral membrane protein of the Golgi apparatus involved in the sialylation of N-linked glycans. A series of experiments has shown that the 17-residue transmembrane domain of ST is sufficient to confer localization to the Golgi apparatus when transferred to the corresponding region of a cell surface type II integral membrane protei...

We have previously hypothesized that ring-opened metabolites may play an important role in benzene toxicity. In this paper we review recent work related to this hypothesis. trans,trans-Muconaldehyde (TTM), a six-carbon diene dialdehyde, was shown by our laboratory to be a microsomal metabolite of benzene. This compound is a ring-opened metabolite of benzene that is hematotoxic in mice. The toxi...

The UDP-glucuronosyltransferase (UGT) system fulfils a pivotal role in the biotransformation of potentially toxic endogenous and exogenous compounds. Here we report that the activity of UGT in rat liver is stimulated by UDP-xylose. This stimulation was found in native microsomal vesicles as well as in the intact endoplasmic reticulum (ER) membrane, as studied in permeabilized hepatocytes, indic...

3-O-Methyl-D-glucose transport across the plasma membrane of isolated rat hepatocytes was followed for net entry of the sugar into sugar-free cells (zero trans entry), net exit of sugar into sugar-free medium (zero trans exit) and for unidirectional entry and exit fluxes when cells had been equilibrated with sugar in the extracellular medium (equilibrium exchange entry and exit). These measurem...

In vitro, dendritic cells (DCs) bind and transfer intact, infectious HIV to CD4 T cells without first becoming infected, a process known as trans-infection. trans-infection is accomplished by recruitment of HIV and its receptors to the site of DC-T cell contact and transfer of virions at a structure known as the infectious synapse. In this study, we used fluorescent microscopy to track individu...

Gram- negative bacteria utilize a diverse array of multidrug transporters to pump toxic compounds out of the cell. Some transporters, together with periplasmic membrane fusion proteins (MFPs) and outer membrane channels, assemble trans-envelope complexes that expel multiple antibiotics across outer membranes of Gram-negative bacteria and into the external medium. Others further potentiate this ...

A small (96-aa) protein, virus protein R (Vpr), of human immunodeficiency virus type 1 contains one hydrophobic segment that could form a membrane-spanning helix. Recombinant Vpr, expressed in Escherichia coli and purified by affinity chromatography, formed ion channels in planar lipid bilayers when it was added to the cis chamber and when the trans chamber was held at a negative potential. The...

introduction: recent studies have shown the presence of cl- channels in heart and liver mitochondrial membranes. in this work, we have characterized the functional profile of a cl- channel from rat brain mitochondria. methods: after removing and homogenizing the rat brain, the supernatant was separately centrifuged in msedigitonin, h2o and na2co3 and mitochondrial inner membrane vesicles were o...