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. 1998 Jan 6;95(1):346–351. doi: 10.1073/pnas.95.1.346

Figure 3.

Figure 3

Competition of isoproterenol for [125I]CYP binding to rat cardiac membranes (A and B) and S49 cyc− membranes (C and D). (A and B) Cardiac membranes (10 μg) were incubated with 75 pM of [125I]CYP and isoproterenol in the absence (•) and presence of 100 μM suramin (▪, A), 10 μM NF503 (▪, B), 100 μM GTP[γS] (▿), the combination of GTP[γS] + suramin (▾, A), or GTP[γS] + NF503 (▾, B). (C and D) S49 cyc− membranes (∼3 μg/25 μl) were preincubated in the absence (C; ○, D) or presence of 3 pmol of rGsα-s and 10 pmol of βγ dimer (•, ▾, and ▪, D). The reaction was started with 75 μl of buffer containing [125I]CYP (to give 150 pM) and isoproterenol in the absence (○, •) or presence of 100 μM GTP[γS] (▿, C; ▾, D) or of 10 μM NF503 (▪). Specific binding in the absence of isoproterenol (∼1.2 and 1.4 fmol of [125I]CYP bound in cardiac and cyc− membranes, respectively) was set 100%.