The first person generally credited with fulfilling the functions of the modern director was:

The first person generally credited with fulfilling the functions of the modern director was George, Duke of Saxe- Meiningen. Meiningen was a wealthy aristocrat and head of a small German principality. In 1826, George, Duke of Saxe- Meiningen and his morganatic wife started an experimental acting group which was one of the first companies in which the importance of the director was stressed.

this protocol provides a detailed procedure for co-immunoprecipitation (co-ip) to identify protein–protein interactions.