Concept #2: Inactivation of cAMP & PKA

Example #1: Order each of the steps in the activation of PKA (by numbering them 1-4 ; first step is already numbered for you) starting after adenylate cyclase activation.

Practice: Which of the following statements about protein kinase A (PKA) is false?

Concept #3: Inactivation of cAMP & PKA

Practice: Which of the following is/are associated with cAMP binding to cAMP-dependent protein kinase A (PKA)? 

I. cAMP binds to the regulatory subunits.
II. Tetrameric regulatory subunits and catalytic subunits dissociate.
III. Catalytic subunits phosphorylate proteins with specific Ser and Thr residues.
IV. cAMP is membrane bound via a phosphoinositol covalent attachment.

Practice: What is the function of a phosphatase?

Practice: What could be the result of a mutation in the R subunits of cAMP-dependent protein kinase A (PKA) that inhibits formation of the R2C2 protein complex?

Practice: The image below is a schematic representation of PKA activation from epinephrine binding. Based on the provided numbers in the diagram, how many subunits of catalytically active PKA will there be?