A cup full of functions

Data from different laboratories have recently indicated that Cup is a multi-functional protein acting both during Drosophila ovary development and early embryogenesis. Cup directly and/or indirectly affects the activity of different mRNAs and proteins to achieve a broad range of biological functions: (1) Cup interacts with Nanos to promote maintenance and survival of the female germ-line stem cells; (2) it binds eIF4E and 3'-UTR-bound factors to repress translation of oskar and nanos mRNAs; (3) it interacts genetically with eIF4E to control translation initiation during ovary development and growth; (4) it may play a role in the control of the phosphorylation status of eIF4E within the developing ovary; finally, (5) it possesses nucleo-cytoplasmic shuttling properties thus pointing to a still uncharacterized function in the cell nucleus. A multi-disciplinary approach, ranging from genetics to proteomics, will be required to shed light on the diverse molecular mechanisms involving Cup and the growing family of its specific interactors.