The cyclic AMP second messenger system is often called the learning pathway.
Neurotransmitters can act directly on ion channels to modify the permiability of cells to ions.
Rutabaga is an adenyl cyclase that creates cAMP in response to neurotransmitter signaling. G-proteins are biochemical marvels. Upon receptor activation, heterotrimeric G-proteins bind GTP and dissociate into constituent parts which in turn initiate further signal transduction. We are thus brought by a second route to Rutabaga, an adenyl cyclase of the fly, and its potential role in transmitting G-protein coupled receptor signaling to activate cell responses. This is discussed in the dunce and rutabaga sites and at sites for other genes involved in the cAMP second messenger pathway.