Isoproterenol-initiated beta-adrenergic receptor diacytosis in cultured cells.
The kinetics of the return of internalized beta-adrenergic receptors to the plasma membrane were measured in human astrocytoma cells. The movement of [125I]iodopindolol-labeled receptors back to the plasma membrane was measured directly and was shown to occur with a t1+2 of 3-4 min. Unlabeled receptors appeared to exhibit the same kinetics of externalization. The process was not inhibited by low concentrations (1-10 microM) of propranolol or even high concentrations of isoproterenol (0.1-1.0 mM). Higher concentrations of propranolol (0.1-1.0 mM) and other lipophilic amines inhibited externalization. The results are consistent with the proposal that catecholamine-induced beta-adrenergic receptor internalization and externalization (diacytosis) occur via the clathrin-coated pit/endosome pathway.
Department of Pharmacology, University of North Carolina, Chapel Hill 27514.
J B
JB
Kurz
J P
JP
Perkins
D000319:Adrenergic beta-Antagonists / Q000378:metabolism; D001254:Astrocytoma / Q000648:ultrastructure; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D006207:Half-Life; D006801:Humans; D007457:Iodine Radioisotopes; D007545:Isoproterenol / Q000494:pharmacology*; D007700:Kinetics; D010869:Pindolol / Q000031:analogs & derivatives / Q000378:metabolism; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D014407:Tumor Cells, Cultured
D000319:Adrenergic beta-Antagonists; D007457:Iodine Radioisotopes; D011943:Receptors, Adrenergic, beta; C029247:3-iodopindolol; D010869:Pindolol; D007545:Isoproterenol