Method for highly sensitive detection of protein-protein interaction

An isolated DNA coding for a fusion protein consisting of a first peptide of a sequence selected from the group consisting of SEQ ID NO:

• 2, SEQ ID NO:
• 3, SEQ ID NO:
• 4, SEQ ID NO:
• 5 and SEQ ID NO:
• 6, and a second peptide, wherein the second peptide does not comprise a sequence of Pyrearinus termitilluminans luciferase, and wherein said fusion protein provides increased luminescence in a split luciferase assay.

A kit for detecting the binding of a first fusion protein and a second fusion protein in the presence of a third moiety that binds to both the first and second fusion proteins, said kit comprising

• an isolated DNA coding for a first fusion protein consisting of a first peptide of the sequence SEQ ID NO:
• 1, and a second peptide;
• and
• an isolated DNA coding for a second fusion protein consisting of a third peptide of a sequence selected from the group consisting of SEQ ID NO:
• 2, SEQ ID NO:
• 3, SEQ ID NO:
• 4, SEQ ID NO:
• 5 and SEQ ID NO:
• 6, and a fourth peptide,
• wherein the second and fourth protein do not comprise a sequence of Pyrearinus termitilluminans luciferase.