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. Author manuscript; available in PMC: 2012 Dec 13.
Published in final edited form as: J Med Chem. 2011 Oct 3;54(20):7375–7384. doi: 10.1021/jm2009937

Table 4.

Receptor occupancy.

Compound [RL] at 5% of forskolin response [RL] at 10% of forskolin response [RL] at 25% of forskolin response
NB397-1×MSH(4) 13000 ± 1000 60000 ± 4900 420000 ± 34000
NB399-2×MSH(4) 12000 ± 1300 45000 ± 4100 400000 ± 22000
NB341-3×MSH(4) 14000 ± 1000 75000 ± 5400 450000 ± 33000

Receptor occupancy was calculated for the concentration of each ligand required to activate cAMP increase at 5%, 10% and 25% of the maximum observed with forskolin (10 μM) treatment using the following established equation: [RL] = Bmax ×x [L] / [L] + Kd. The Kd values used for this calculation were estimated from the competition binding assays (Figure 3). The numbers of receptors was assumed to be constant at 7.5 × 105 receptors per cell, as previously measured for this cell line32.