Fig. 1.

Characterization of the model system of transformed s49 ck cell lines. A, Saturation-binding curve. Specific binding was measured after a 5 h incubation with ¹²⁵I-hCG at 37 C for the mock (■) and LHR⁺ s49 ck (●) cells, and the derived K_d and B_max values for the LHR⁺ cells are 4.5 ± 0.4 nm and (24 ± 1.2) × 10³ receptors per cell, respectively. B, Dose-response curve. The cAMP response was measured after a 30-min incubation with hCG (37 C) of the LHR⁺/mock (■) and LHR⁺/Gα_s⁺ (●) transformed cell lines, and the values found for EC₅₀ and R_max for the LHR⁺/Gα_s⁺ cell line are 0.34 ± 0.1 nm and 11.2 ± 0.2 pmol/10⁶ cells, respectively. Data are presented as mean ± sem.