Live-cell structural biology to solve biological mechanisms: the case of the exocyst

Historically, structural biology has been largely centered on in vitro approaches as the dominant technique to obtain indispensable high-resolution data. In situ structural biology is now poised to contribute with high-precision observations in a near-physiological context. Mass spectrometry, electron tomography, and fluorescence microscopy are opening up new opportunities for structural analysis, including the study of the protein machinery in living cells. The complementarity between studies is increasingly used to reveal biologically significant observations. Here we compare two complementary studies addressing the mechanisms of vesicle tethering with in vitro and in situ approaches. Cryoelectron microscopy and live-cell imaging assisted by anchoring platforms team up to explore elusive mechanisms of exocytosis, showing directions of future research.