Properties of β-adrenergic receptors in untreated and butyrate-threated HeLa cells |
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Authors: | John F Tallman Craig C Smith Richard C Henneberry |
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Institution: | 1. Section on Biochemistry and Pharmacology, Biological Psychiatry Branch, National Institute of Mental Health, USA;2. Laboratory of Molecular Biology, National Institute of Neurological and Communicative Disorders and Stroke, Bethesda, Md. 20014 U.S.A. |
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Abstract: | HeLa cells contain receptors on their surface which are β-adrenergic in nature. The binding of (?)-3H]dihydroalprenolol is rapid, reversible, stereo-specific and of relatively high affinity. The HeLa cells also contain an adenylate cyclase which is activated by (?)-isoproterenol > (?)-epinephrine > (?)-norepinephrine. The adenylate cyclase of HeLa is also activated by guanyl-5′-yl-imidodophosphate (Gpp(NH)p), a nonhydrolyzable analogue of GTP. Inclusion of both (?)-isoproterenol and Gpp(NH)p leads to approximately additive rathen than synergistic activation of adenylate cyclase. After treatment of HeLa cells with 5 mM sodium butyrate there is an increase in the number of β-adrenergic receptors, but not in their affinity, which is reflected in an increased ability of (?)-isoproterenol to activate adenylate cyclase. Other properties of the β-adrenergic receptor including association and dissociation rates, temperature optimum of adenylate cyclase and response to Gpp(NH)p are relatively unaffected by butyrate pretreatment of the cells. |
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Keywords: | HEPES Gpp(NH)p guanyl-5′-yl-imidodiphosphate |
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