System to detect protein-protein interactions

A method for detecting an interaction between a first test protein and a second test protein, the method comprising:

• (a) providing a host cell containing a detectable gene wherein the detectable gene expresses a detectable protein when the detectable gene is activated by an amino acid sequence including a transcriptional activation domain when the transcriptional activation domain is in sufficient proximity to the detectable gene;
• (b) providing a first chimeric gene that is capable of being expressed in the host cell, the first chimeric gene comprising a DNA sequence that encodes a first hybrid protein, the first hybrid protein comprising:
• (i) a DNA-binding domain that recognizes a binding site on the detectable gene in the host cell;
• and
• (ii) a first test protein or fragment thereof that is to be tested for interaction with at least one second test protein or fragment thereof;
• (c) providing a second chimeric gene that is capable of being expressed in the host cell, the second chimeric gene comprising a DNA sequence that encodes a second hybrid protein, the second hybrid protein comprising:
• (i) the transcriptional activation domain;
• and
• (ii) a second test protein or fragment thereof that is to be tested for interaction with the first test protein or fragment thereof;
• wherein interaction between the first test protein and the second test protein in the host cell causes the transcriptional activation domain to activate transcription of the detectable gene;
• (d) introducing the first chimeric gene and the second chimeric gene into the host cell;
• (e) subjecting the host cell to conditions under which the first hybrid protein and the second hybrid protein are expressed in sufficient quantity for the detectable gene to be activated;
• and
• (f) determining whether the detectable gene has been expressed to a degree greater than expression in the absence of an interaction between the first test protein and the second test protein.