Davis P J, Handwerger B S, Gregerman R I
J Clin Invest. 1972 Mar;51(3):515-21. doi: 10.1172/JCI106839.
Thyroxine-binding prealbumin (TBPA) in normal human serum has been shown in a polyacrylamide gel electrophoresis system to bind 7-9% of tracer level purified [(125)I]triiodothyronine (T3), and more than 30% of T3 in serum deficient in thyroxinebinding globulin (TBG). The T3-TBPA interaction has been confirmed at pH 9.0 and pH 7.4 in this electrophoretic demonstration of TBPA binding of T3 in serum. Purified human TBPA has also been shown to bind T3. Progressive additions of unlabeled thyroxine (T4) to serum containing tracer [(125)I]T3 displace T3 from TBG, its principal carrier, to TBPA and albumin; however, T4 loading does not lead to significant T3 displacement from TBPA even at T4 levels known to saturate TBPA. Loading of serum with unlabeled T3 results in displacement of more than 50% of [(125)I]T3 from TBPA, as well as from TBG, to albumin. Studies carried out with serum containing diphenylhydantoin (DPH) or MK-185, known inhibitors of T4 binding by TBG, also showed T3 displacement from TBG to TBPA and albumin. Although salicylate and tetraiodothyroacetic acid (TETRAC) displace T4 from sites on TBPA, they have only minimal effects on T3-TBPA interaction.
在聚丙烯酰胺凝胶电泳系统中已表明，正常人血清中的甲状腺素结合前白蛋白（TBPA）能结合7% - 9%的示踪水平纯化的[（125）I]三碘甲状腺原氨酸（T3），而在甲状腺素结合球蛋白（TBG）缺乏的血清中，TBPA能结合超过30%的T3。在该电泳实验中，于pH 9.0和pH 7.4条件下均证实了血清中TBPA与T3的相互作用。纯化的人TBPA也已被证明能结合T3。向含有示踪剂[（125）I]T3的血清中逐步添加未标记的甲状腺素（T4），会使T3从其主要载体TBG转移至TBPA和白蛋白；然而，即使在已知能使TBPA饱和的T4水平下，T4的加载也不会导致T3从TBPA上显著解离。用含有苯妥英（DPH）或MK - 185（已知的TBG结合T4的抑制剂）的血清进行的研究也表明，T3从TBG转移至TBPA和白蛋白。尽管水杨酸盐和四碘甲状腺乙酸（TETRAC）能使T4从TBPA上的位点解离，但它们对T3 - TBPA相互作用的影响极小。
