They exhibit strong excimer emission around 515 nm, which is used to monitor interaction of metal ions with the ionophores.
The technique is so precise that it can be used to monitor these interactions in single dendritic spines, the tiny finger-like projections on nerve cell branches at which signalling takes place.
Fluorescence correlation spectroscopy (FCS) is frequently used to monitor molecular interactions (binding and unbinding), chemical reaction kinetics and diffusion constants of fluorescent molecules.
Another is time-resolved luminescence resonance energy transfer (LRET), which has been used to monitor protein interactions in cells; this technique takes advantage of a luminescent terbium complex and luminescent energy transfer to GFP [ 30].
Split TEV has been used to monitor protein protein interactions, and this concept appears to be generalizable to reconstitution of many proteins, as similar systems using split GFP, split luciferase, or split beta-lactamase have been developed.
Förster resonance energy transfer (FRET) technology is widely used to monitor protein/protein interactions, coupling fluorophore pairs such as cyan fluorescent protein (CFP) and yellow fluorescent protein (YFP) to two proteins of interest.
Similarly, these techniques have been used to monitor the interactions of epithelial and stromal cells with tumors, as well as the initiation of collagen remodeling (Brown et al., 2003; Condeelis and Segall, 2003; Perentes et al., 2009; Wolf et al., 2009).
FRET can also be used to monitor protein protein interactions, oligomer formation and conformational changes within oligomers by labeling one pool of IDPs with a donor and another pool with an acceptor, or by energy transfer between labeled IDPs and dyes, such as thioflavin T, that bind to specific oligomeric species.
Because FRET strongly depends on the distance between donor and acceptor and occurs only on the nanometer scale, FRET can be used to monitor protein protein interactions for proteins fused to fluorophores or conformation changes of a protein tagged with two fluorophores.
