Table 2.

G protein α-subunits

G Protein α-Subunit	Downstream Effects
Gαs	Activate adenylyl cyclase → increase cAMP → activate PKA
Gαi/Gαo	Inhibit adenylyl cyclase → decrease cAMP
Gαq/Gα11	Activate phospholipase Cβ: IP3 generation → intracellular Ca2+ and diacylglycerol → protein kinase C
Gα12/Gα13	RhoGEF → RhoA → activate Rho kinase

Shown is a summary of G protein α-subunits that bind to G protein-coupled receptors and their general downstream effects. IP₃, inositol 1,4,5-trisphosphate; RhoGEF; rho-specific guanine nucleotide exchange.