This application of this knowledge is achieved by splitting the yeast Gal4 gene in two parts - the activating domain (in yellow above and below) and the binding domain (in white above and below) . The split protein does not work unless the two parts are in physical contact. It is possible to make the two parts come in contact by making two chimeric proteins where each of the two parts are translationally fused to two other proteins which interact - i.e. an artificial gene which is transcribed to make a single protein). The chimera interact with each other resulting in a transcriptional activation of the beta-galactosidase. Simple isn’t it ? (-: see below to see how this is achieved.
