Method for performing in-situ quantitation determination on protein-protein interaction in living cell with FRET (fluorescence resonance energy transfer) method

The invention discloses a method for determining whether interaction exists between first protein and second protein in a cell with an FRET (fluorescence resonance energy transfer) method. The method comprises the following steps: (1), first fusion protein and second fusion protein are expressed in the cell, wherein the first fusion protein comprises the first protein and first closable fluorescent protein serving as a donor, and the second fusion protein comprises the second protein and second closable fluorescent protein serving as a receptor; (2), under the 3 conditions that the first closable fluorescent protein and the second closable fluorescent protein are open, the first closable fluorescent protein is open independently and the second closable fluorescent protein is open independently, the fluorescence values of the cell are detected under the conditions of three types of exciting light and emitted light respectively, so that a data set comprising fluorescence absolute values can be acquired; (3), the value of a parameter FR is determined on the basis of the data set, and whether the interaction exists between the first protein and the second protein is determined on the basis of the obtained value of the parameter FR.