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GFP fluorescence can be modulated in mammalian cells by binding to single-chain antibodies (nanobodies), selected to make GFP brighter or dimmer; these changes are explained by the crystal structures of the GFP-nanobody complexes. The applications of such nanobodies to monitor protein expression and subcellular localization in real time are explored.
Screening a library of artificial zinc fingers for transcriptional activators in mammalian cells can be laborious. Now a strategy is described that couples the screening to production of retroviral particles that will carry the positive clones, allowing iterative rounds of selection.
