A method of finding unknown proteins of a specific function

...by creating an artificial protein of this specific function of interest.

I know it is not so much related to appetite regulation but I still think it's cool!

Details
In cellular biology, scientists can design an artificial protein structure. Then they can go and look into 100,000s let's say yeast colonies and see what mutant cells can't exist without this protein structure. When they find these mutants, saved by the protein, they can see what the mutant gene/protein is and go on and fully characterise it.

So simply by designing an artificial protein structure of a known function, endogenous proteins of this same functionality can be find and characterised.

Reference: http://www.sciencemag.org/content/325/5939/477.abstract Kornmann et al., 2009. An ER-Mitochondria Tethering Complex Revealed by a Synthetic Biology Screen. Science, 325(5939), 477-481.