primary messenger

ligand

second messenger

cross talk

β-adrenergic receptor (β-AR)

seven-transmembrane-helix (7TM) receptor

rhodopsin

G protein

agonist

G-protein-coupled receptor (GPCR)

420

adenylate cyclase

protein kinase A (PKA)

β-adrenergic receptor kinase

phosphoinositide cascade

phosphatidylinositol 4,5-bisphosphate (PIP₂)

phospholipase C

protein kinase C (PKC)

calmodulin (CaM)

EF hand

calmodulin-dependent protein kinase (CaM kinase)

insulin

insulin receptor

tyrosine kinase

receptor tyrosine kinase

insulin-receptor substrate (IRS)

pleckstrin homology domain

adaptor protein

Src homology 2 (SH2) domain

epidermal growth factor (EGF)

EGF receptor (EGFR)

dimerization arm

Src homology 3 (SH3) domain

Ras

small G protein

guanine-nucleotide-exchange factor (GEF)

extracellular signal-regulated kinase (ERK)

GTPase-activating protein (GAP)

oncogene

proto-oncogene

tumor-suppressor gene