Cover Picture

The cover picture shows a schematic representation of events accompanying the uptake of ligands decorated with mannosides or mannose bioisosteres by dendritic cells. According to the known mannose receptor mediated uptake pathway, the mannosylated molecule (green with black attachments) forms a complex with the mannose receptor (red). This complex is rapidly transported into the early endosomes (red arrow). The mannose receptor is separated from its ligand at slightly acidic pH values and is efficiently recirculated to the cell membrane surface (purple arrows), while the ligand follows the endolysosomic pathway (yellow arrow). The green arrow represents nonspecific pinocytosis. Confocal microscopy experiments suggest that the uptake of polyquinoylated glycomimetics follows the mannose receptor mediated pathway; the tetraquinoylated constructs, the mannose receptor, and the nucleus are analyzed for green, red, and blue fluorescence, respectively. Inset (a), taken after 5 min, shows the internalized fluorescein‐labeled glycomimetic is fully colocalized with the mannose receptor in vesicles close to the cell membrane. Inset (b) shows that after 20 min the ligand signal is localized in vesicles devoid of mannose receptor, which are situated further into the cell. For more details, see the article by C. Grandjean, H. Gras‐Masse, and co‐workers on p. 747 ff.