Oxysterol-binding protein (OSBP)-related protein 4 (ORP4) is essential for cell proliferation and survival.

Oxysterol-binding protein (OSBP) and OSBP-related proteins (ORPs) comprise a large gene family with sterol/lipid transport and regulatory activities. ORP4 (OSBP2) is a closely related paralogue of OSBP, but its function is unknown. Here we show that ORP4 binds similar sterol and lipid ligands as OSBP and other ORPs but is uniquely required for the proliferation and survival of cultured cells.

Functional implications of sterol transport by the oxysterol-binding protein gene family.

Cholesterol and its numerous oxygenated derivatives (oxysterols) profoundly affect the biophysical properties of membranes, and positively and negatively regulate sterol homoeostasis through interaction with effector proteins. As the bulk of cellular sterols are segregated from the sensory machinery that controls homoeostatic responses, an important regulatory step involves sterol transport or signalling between membrane compartments. Evidence for rapid, energy-independent transport between organelles has implicated transport proteins, such as the eukaryotic family of OSBP (oxysterol-binding protein)/ORPs (OSBP-related proteins).

Electric field induced assembly of vimentin microscaffolds around metallic electrodes.

The self-assembly properties of fibrous proteins such as collagen are frequently used to form three-dimensional scaffolds. In this study we investigated the effect of nonuniform alternating and static electric-fields on the self-assembly properties of a dilute solution of vimentin. In the presence of both types of fields at the same time, vimentin was observed to accumulate at the positive electrode and to form microscaffolds bridging the two electrodes in 20-30 min.