Method for detecting protein-protein interaction

1. A method for detecting an interaction between a first protein and a second protein, the method comprising the steps of:

expressing in a cell a first fusion protein comprising the first protein and an association-inducing protein, and a second fusion protein comprising the second protein and a fluorescent protein having a multimerization ability and able of emitting fluorescence;

determining that there exists an interaction between the first protein and the second protein by detecting a fluorescent focus, wherein

the association-inducing protein is at least one protein selected from the group consisting of PB1 domain of p62, a PB1 domain of TFG, a PB1 domain of PKCiota, a SAM domain of TEL, a SAM domain of DGK delta, and a SAM domain of Tankyrase-1;

the fluorescent protein having a multimerization ability is at least one fluorescent protein selected from the group consisting of a fluorescent protein capable of forming a homomultimer, monomeric Kusabira-Orange 2, monomeric Keima-Red, monomeric Midoriishi-Cyan1, monomeric Kusabira-Orange 1, and monomeric Kikume Green-Red1; and

the fluorescent focus has a fluorescence intensity in a region of 0.2 to 5 μm, the fluorescence intensity being higher than a fluorescence intensity of the fluorescent protein which is present in a dispersed state in the cell, and wherein the association inducing protein is able to form a fluorescent focus when fused to the fluorescent protein having an multimerization ability.

2. The method of claim 1 , further detecting the presence of the interaction between the first protein and the second protein for a period of time wherein the absence of the focus indicates the ending of the interaction.

3. The method of claim 2 , further comprising adding a stimulus to the cell.

4. The method of claim 3 , wherein the interaction ends in response to a stimulus and further comprising measuring a time period from applying the stimulus to the cell to extincting the focus.