Cover photograph (Copyright © 2007, American Society for Microbiology. All Rights Reserved.): Confocal microscopic image of potato virus X (PVX) TGBp2 protein fused to green fluorescent protein (GFP). TGBp2, one of three PVX proteins responsible for virus intercellular movement, has two transmembrane domains and a central conserved segment. Wild-type GFP-TGBp2 associates with granular endoplasmic reticulum-derived vesicles. However, mutation of one residue within the central conserved element causes GFP-TGBp2 (green) to accumulate in enlarged vesicles neighboring the plasma membrane. This image shows mutant PVX-infected tobacco leaf epidermal cells at the base of a trichome treated with FM4-64 dye, which produces a red fluorescence in the plasma membrane and endosome. (See related article on page 1899.)