Smith B R, Pyle G A, Petersen V B, Hall R
J Endocrinol. 1977 Dec;75(3):391-400. doi: 10.1677/joe.0.0750391.
The relationship between the binding of thyrotrophin (TSH) to receptors and the production of cyclic AMP has been investigated using crude human thyroid membranes. Receptor binding was studied by use of 125I-labelled bovine TSH, which had been purified by adsorption to and elution from human thyroid membranes. This 125I-labelled material showed the same biological activity as the unlabelled hormone. Binding studies at equilibrium indicated that the association constant of the TSH-membrane interaction decreased as the amount of TSH bound increased. Kinetic data did not provide definite evidence that this was due to an effect of increasing receptor occupancy on the dissociation rate constant. Detectable stimulation by TSH of cyclic AMP production by the membranes was observed with as little as 30 micromicron. (1 ng) hormone. Increasing amounts of TSH over the range 0-250 micromicron caused increases in the production of cyclic AMP, proportional to the amount of hormone bound. With larger amounts of TSH, increasingly greater amounts of bound hormone were required to give corresponding increases in cyclic AMP formation, and addition of TSH in amounts greater than 16 millimicron resulted in progressive inhibition of cyclic AMP formation. Kinetic studies indicated that receptor binding was not rate-limiting in the stimulation of cyclic AMP production by TSH.
利用粗制的人甲状腺膜研究了促甲状腺激素（TSH）与受体结合及环磷酸腺苷生成之间的关系。通过使用经人甲状腺膜吸附和洗脱纯化的125I标记牛TSH来研究受体结合。这种125I标记物质显示出与未标记激素相同的生物活性。平衡结合研究表明，TSH与膜相互作用的缔合常数随着结合的TSH量增加而降低。动力学数据没有提供确凿证据表明这是由于受体占有率增加对解离速率常数的影响所致。观察到低至30微微摩尔（1纳克）激素就能检测到TSH对膜生成环磷酸腺苷的刺激作用。在0 - 250微微摩尔范围内增加TSH的量会导致环磷酸腺苷生成增加，与结合的激素量成正比。对于大量的TSH，需要越来越多的结合激素才能使环磷酸腺苷形成相应增加，并且添加量大于16毫微摩尔的TSH会导致环磷酸腺苷形成逐渐受到抑制。动力学研究表明，在TSH刺激环磷酸腺苷生成过程中，受体结合不是限速步骤。
