Now, in the pathway that we described so far, this pathway involves only our first messenger. And the first messenger binds and causes that action potential to take place. Now, in most other signal transduction processes we have the use of another molecule known as the secondary messenger. And these types of pathways are known as secondary messenger systems. And secondary messenger systems are most often controlled by special protein complexes that involve g protein. So what exactly is the pathway of such a signal transduction process?