The decrease in cAMP

The activation of adenylyl cyclase

Downstream activation of PKA

Adenyl cyclase hydrolysis of ATP

An inactivated alpha subunit of the G protein

Synthesis of beta-hydroxybutyrate

Dissociation of G protein subunits

Breakdown of phosphatidylinositol bisphosphate

Activation of protein kinase A

Activation of phosphodiesterases

Four molecules of cAMP bind to PKA and dissociate it into 2 catalytic subunits and 2 regulatory subunits

cAMP phosphorylates PKA which sets it into action.

cAMP is initially bound to PKA to prevent its action, and when it dissociates PKA is able to function

cAMP does not affect the action of PKA

Four molecules of cAMP bind only to the catalytic subunits of PKA which allows them to function

G-protein

Calcium

cAMP

cGMP

diacylglycerol

Conversion of ATP to cAMP

Conversion of ATP to ADP

Conversion of cAMP to ATP

Conversion of GTP to GDP

Conversion of GDP to GTP

II only

I only

I and III

I, II, and III

I, II, III, and IV

I and II

II, III, and IV

II and III

III and IV

They allow for signifiant amplification of a signal within a cell

They allow for the production of only one kind of molecule

They allow a single signal to cause endless, unceasing production of some final product

They allow ligands to bind to multiple types of receptors

They allow receptors to be receptive to multiple types of ligands

activated . . . not activated

activated . . . activated

not activated . . . activated

not activated . . . not activated

Converts phosphatidylinositol biphosphate (PIP2) into diacylglycerol (DAG) and inositol triphosphate (IP3)

Converts diacylglycerol (DAG) into phosphatidylinositol biphosphate (PIP2) and inositol triphosphate (IP3)

Converts inositol triphosphate (IP3) into phosphatidylinositol biphosphate (PIP2) and diacylglycerol (DAG)

Forms phosphatidylinositol biphosphate (PIP2) from diacylglycerol (DAG) and inositol triphosphate (IP3)

Forms diacylglycerol (DAG) from inositol triphosphate (IP3) and phosphatidylinositol biphosphate (PIP2)