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. Author manuscript; available in PMC: 2012 Jul 28.
Published in final edited form as: J Recept Signal Transduct Res. 2010 Aug 23;30(6):372–375. doi: 10.3109/10799893.2010.508165

Figure 2.

Figure 2

The Mg-dependence of the activation of Gs by GTPγS is shifted from the millimolar concentration range to the micromolar concentration range by the liver membrane glucagon receptor. (A) Three-step assay design: 1. adenylyl cyclase in liver membranes is inactivated with N-ethylmaleimide (NEM); 2. Gs in membranes is activated by GTPγS and increasing concentrations of Mg2+, in the absence and in the presence of glucagon; 3. the activation status of Gs is assessed by extraction with cholate and reconstitution of Mg-dependent adenylyl cyclase activity in membranes from Gs-deficient “cyc-“ S49 cells. B. Effect of Mg and glucagon during step 2. Adapted from ref. 5.