Identification and characterization of a new binding site for angiotensin II in mouse neuroblastoma neuro-2A cells.
Specific binding site for 125I-angiotensin II (Ang II), with unique pharmacological properties uncommon to the hitherto recognized receptor subtypes, was observed in mouse neuroblastoma cells (Neuro-2A). Differentiation of the cells with 100 nM PGE1 resulted in a 10-fold increase in the number of Ang II binding sites without changing the binding affinity (Kd value: 12.0 nM). 125I-Ang II binding to membranes of differentiated Neuro-2A was inhibited by unlabeled Ang II with a Ki value of 7.06 +/- 1.09 nM but not by Ang III (1 microM). Both AT1 antagonist, Dup753, and AT2 antagonist, PD123319, failed to inhibit 125I-Ang II binding at 1 microM. 125I-Ang II binding was not affected by GTP analogs such as GTP gamma S and Gpp(NH)p. These results suggest that Neuro-2A cells possess a binding site for Ang II which is different from the presently known subtypes of Ang II receptors, and that the number of the binding site is regulated by cell differentiation.
Chaki
S
S
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232.
Inagami
T
T
D000804:Angiotensin II / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004229:Dithiothreitol / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D009447:Neuroblastoma; D011945:Receptors, Angiotensin / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*
D011945:Receptors, Angiotensin; D000804:Angiotensin II; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D004229:Dithiothreitol