Endocrinology, Vol 134, 7-10, Copyright © 1994 by Endocrine Society

ARTICLES

Receptor-G-protein coupling in desensitization-resistant mutant adrenal cells

MF Olson and BP Schimmer
Banting and Best Department of Medical Research, University of Toronto, Ontario, Canada.

Mutant isolates from the Y1 mouse adrenocortical tumor cell line (designated Y1DR) were previously shown to resist homologous desensitization of adenylyl cyclase via endogenous ACTH receptors or transfected beta 2-adrenergic receptors. To further localize the site of the DR mutation, we examined the agonist-binding properties of the transfected beta 2-adrenergic receptor in parental Y1 cells and the DR mutant before and after desensitization with the beta-adrenergic agonist isoproterenol. Binding studies were carried out using [125I]iodocyanopindolol as the labeled ligand and isoproterenol as the competing agonist. We found that the DR mutant has a greater number of high affinity receptors in the basal state than does the Y1 parent (70- 80% vs. < or = 50%) and that treatment of membranes from parent or mutant cells with guanyl-5'-yl imidodiphosphate and NaCl converts all of the high affinity sites to low affinity sites. After desensitization with isoproterenol, only low affinity binding sites are detected in parental Y1 cells, whereas the DR mutants retain an appreciable number of high affinity receptors. These results indicate that the DR mutant may resist desensitization by affecting agonist-induced uncoupling of receptors from their guanyl nucleotide-binding regulatory G-proteins.

This article has been cited by other articles:

				C. M. Colantonio, W.-K. Kwan, W. Czerwinski, J. Mitchell, and B. P. Schimmer Altered G Protein Activity in a Desensitization-Resistant Mutant of the Y1 Adrenocortical Tumor Cell Line Endocrinology, February 1, 1998; 139(2): 626 - 633. [Abstract] [Full Text] [PDF]

				B. P. Schimmer, J. Tsao, and W. Czerwinski Amplification of the Transketolase Gene in Desensitization-resistant Mutant Y1 Mouse Adrenocortical Tumor Cells J. Biol. Chem., March 1, 1996; 271(9): 4993 - 4998. [Abstract] [Full Text] [PDF]