Now, we can categorize protein kinases into two groups. On one side we have a group called dedicated protein kinases and on the other side we have a group known as multifunctional protein kinases. Now, what exactly is the difference between these two groups? Well, dedicated protein kinases basically phosphorylate either a single substrate molecule or a set of closely related substrate molecules. On the other hand, multifunctional protein kinases have the capability of actually catalyzing the phosphorylation of many different types of enzymes and many different types of protein molecules. Now, the first question I'd like to address is what exactly determines the specific nature of protein kinases?