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Parallel inactivation of α 2 ‐adrenergic agonist binding and N i by alkaline treatment
Author(s) -
Kim Marian H.,
Neubig Richard R.
Publication year - 1985
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(85)80134-4
Subject(s) - agonist , chemistry , gtp' , cyclase , pertussis toxin , adrenergic agonist , g protein , binding site , adenylate kinase , endocrinology , receptor , medicine , biochemistry , biology , enzyme
α 2 ‐Adrenergic receptor‐mediated inhibition of adenylate cyclase requires the guanine nucleotide‐binding protein, N i . This protein may also be required for stabilization of high‐affinity α 2 ‐adrenergic agonist binding. Human platelet membranes treated under alkaline conditions (pH 11.5) exhibited a selective loss of high‐affinity agonist binding as measured by P ‐[ 3 H]aminoclonidine and [ 3 H]UK 14,304. Binding of the antagonist [ 3 H]yohimbine was largely unaffected with retention of > 60% of control binding sites. N i determined by pertussis toxin‐catalyzed [ 32 P]ADP‐ribosylation of cholate extracts from alkaline‐treated membranes, was also markedly reduced. The parallel loss of of α 2 ‐agonist binding and N i provides additional evidence that N i , is required for α 2 ‐adrenergic agonist binding.