the present invention describes a method for detecting biomolecular interactions said method comprising : selecting an appropriate reporter molecule selected from the group consisting of a protein , a fluorescent protein , a luminescent protein and a phosphorescent protein ; effecting fragmentation of said reporter molecule such that said fragmentation results in reversible loss of reporter function ; fusing or attaching fragments of said reporter molecule separately to other molecules ; followed by reassociation of said reporter fragments through interactions of the molecules that are fused to said fragments ; and detecting said biomolecular interactions by reconstitution of activity of the reporter molecule with the proviso that said protein is not ubiquitin .