Activation of 7TM receptor (GCPR)

Step 1: Epinephrine binds 7TM receptor (aka GCPR)

Activation of 7TM receptor (GCPR)

Step 2: 7TM receptor changes shape

Step 3: Heterotetramer of G protein breaks, thereby releasing free G-alpha subunit

Step 4: Free G-alpha subunit releases GDP and binds GTP to become the G-alpha S complex

Step 6: G-alpha S complex binds and activates adenyl cyclase

Step 7: Adenyl cyclase converts many ATPs to cyclic AMPs (cAMPs)

Step 8: cAMPs activate protein kinases

Step 9: Signal amplification

Step 10: Product is made

Step 8: [cAMP] increases

Step 9: Two cAMP molecules bind to each regulatory subunit of PKA

Step 7d: Regulatory and catalytic subunits dissociate

PKA = 2 reg subunits + 2 catalytic subunits

Step 9: PKA phosphorylates Ser and Thr residues of other proteins