Figure 2.

Comparison between the dose dependencies of TSH stimulation of IP1 production and enhanced dissociation of prebound ¹²⁵I-TSH (negative cooperativity). Bars represent means ± sd. A) TSH stimulation of IP1 production. IP1 production was measured as described in Materials and Methods. Results shown are from two experiments performed in duplicate. B) Time course of ¹²⁵I-TSH dissociation. ¹²⁵I-TSH dissociation was performed as described in Materials and Methods in the absence (control) or presence of 100 mU/ml TSH. Results shown are from 2 experiments performed in duplicate. C) TSH stimulation of ¹²⁵I-TSH dissociation. ¹²⁵I-TSH dissociation was performed as described in Materials and Methods in the absence (control) or presence of various concentrations of TSH. Results shown are from 2 experiments performed in triplicate.