EBV-positive human sera contain antibodies against the EBV BMRF-2 protein.

We previously showed that the EBV glycoprotein BMRF-2 contains a functional integrin-binding Arg-Gly-Asp (RGD) domain that plays an important role in viral infection and cell-to-cell spread of progeny virions in oral epithelial cells. In this study, we found that EBV-seropositive human sera contain antibodies against BMRF-2. The inhibitory effect of EBV-positive sera on EBV infection of oral epithelial cells was substantially reduced by pre-incubation of serum samples with the BMRF-2 RGD peptide, suggesting that anti-BMRF-2 human antibodies possess neutralizing activity.

Rab3B regulates ZO-1 targeting and actin organization in PC12 neuroendocrine cells.

Rab3B is a monomeric GTPase that modulates norepinephrine secretion when expressed in PC12 neuroendocrine cells. In the present study we determined whether rab3B also regulates the organization of intercellular junctions, since this GTPase localizes to regions of cell contact in multiple cell types. The stable expression of rab3B, but not the closely related rab3A, led to two morphological phenotypes in PC12 cells: (i) reorganization of F-actin into long filopodia and (ii) redistribution of the junction-associated protein ZO-1.

Lipid modulation of nicotinic acetylcholine receptor function: the role of membrane lipid composition and fluidity.

The effects of membrane lipid composition and fluidity on AChR ion channel function were studied after reconstituting the receptor with sphingomyelin, phosphatidylcholines with different degrees of unsaturation, or different neutral lipids. AChR ion flux activity was shown to be retained in some membranes of both high and low fluidity, as measured by the steady-state anisotropy of the membrane probes diphenylhexatriene and trimethylammonium diphenylhexatriene. The results suggest that lipid composition is more important than bulk membrane fluidity in determining AChR ion channel function.

Lipid modulation of nicotinic acetylcholine receptor function: the role of neutral and negatively charged lipids.

The effects of negatively charged and neutral lipids on the function of the reconstituted nicotinic acetylcholine receptor from Torpedo californica were determined with two assays using acetylcholine receptor-containing vesicles: the ion flux response and the affinity-state transition. The receptor was reconstituted into three different lipid environments, with and without neutral lipids: (1) phosphatidylcholine/phosphatidylserine; (2) phosphatidylcholine/phosphatidic acid; and (3) phosphatidylcholine/cardiolipin. Analysis of the ion flux responses showed that: (1) all three negatively charged lipid environments gave fully functional acetylcholine receptor ion channels, provided neutral lipids were added; (2) in each lipid environment, the neutral lipids tested were functionally equivalent to cholesterol; and (3) the rate of receptor desensitization depends upon the type of neutral lipid and negatively charged phospholipid reconstituted with the receptor.