Potential mechanisms and physiologic actions of intracellular angiotensin II

bAs with other G protein-coupled receptors, type I angiotensin II receptors (AT(1)R) are plasma membrane-associated receptors that bind an extracellul ar agonist and initiate signal transduction pathways that mediate the physi ologic actions elicited by the peptide. After agonist binding, AT(1)R under go endocytosis and, after intracellular ligand dissociation, the receptors recycle to the plasma membrane. There are data from a variety of cell types suggesting that internalization of AT(1)R may be involved in activating a subset of angiotensin It-mediated signaling pathways. The evidence for acti ve cytoplasmic and nuclear angiotensin II receptors is also reviewed; These studies suggest that internalization of peptide and receptor may be a nece ssary step for the transmission of the full range of cellular responses pro duced by angiotensin II.