<prompt> Answer this question truthfullyWhat happens in the first step of the adenylyl cyclase and phospholipase C mechanism of signaling when a hormone binds to its receptor?  <response>: <reason> In the first step of the adenylyl cyclase and phospholipase C mechanism of signaling, binding of hormone to its receptor causes release of GDP from its α subunit αs, αi, or aq and replacement by GTP. 