This animation demonstrates how a potentially useful small molecule can be fished out from the thousands of compounds created by researchers. A protein of interest, calmodulin in this example, can be used as a filter in a “stream” of small molecules. The majority of small molecules will not interact with calmodulin of ten because they lack the correct shape to bind with it. The rare molecule that does bind with calmodulin is the one researchers are looking for and can then be used for further investigations.