Schueler P A, Schwartz H L, Strait K A, Mariash C N, Oppenheimer J H
Department of Medicine, University of Minnesota, Minneapolis 55455.
Mol Endocrinol. 1990 Feb;4(2):227-34. doi: 10.1210/mend-4-2-227.
We have compared the affinities for T3 and the T3 analog binding characteristics of the in vitro translational products of seven c-erbA cDNAs (chicken c-erbA alpha; human placental c-erbA beta; rat c-erbA beta-1; rat c-erbA alpha-1; rat c-erbA alpha-2; human testis c-erbA alpha-2; and human kidney c-erbA alpha-2). Four of these (chicken c-erbA alpha, human placental c-erbA beta, rat c-erbA beta-1, rat c-erbA alpha-1) bound T3 with high affinity as previously described. When compared under identical conditions of synthesis and [125I]T3 binding, there was no significant difference between the affinity of the chicken c-erb A alpha-1 and the human c-erbA beta but in a more limited series the affinity of rat c-erbA beta-1 for T3 was 4.6-fold higher than that of the rat c-erbA alpha-1. In vitro translational products of the beta-probes showed a characteristic 2.2-fold higher triiodothyroacetic acid/T3 ratio than did the products of the alpha-probes, regardless of the species of origin of the probe. As previously established, the rat c-erbA alpha-2 product did not bind T3. However, in contrast to two published reports, the human testis and kidney alpha-2 probe products also failed to bind T3. These findings indicate that highly conserved C-terminal 37-40 residues are important for high affinity T3 binding by proteins encoded by the c-erb A family of genes.
我们比较了7种c-erbA cDNA（鸡c-erbAα；人胎盘c-erbAβ；大鼠c-erbAβ-1；大鼠c-erbAα-1；大鼠c-erbAα-2；人睾丸c-erbAα-2；人肾c-erbAα-2）体外翻译产物对T3的亲和力以及T3类似物的结合特性。其中4种（鸡c-erbAα、人胎盘c-erbAβ、大鼠c-erbAβ-1、大鼠c-erbAα-1）如前所述以高亲和力结合T3。在相同的合成条件和[125I]T3结合条件下进行比较时，鸡c-erbAα-1与人c-erbAβ的亲和力之间没有显著差异，但在一个更有限的系列中，大鼠c-erbAβ-1对T3的亲和力比大鼠c-erbAα-1高4.6倍。β探针的体外翻译产物显示出三碘甲状腺乙酸/T3比值比α探针的产物高2.2倍的特征，无论探针的来源物种如何。如先前确定的，大鼠c-erbAα-2产物不结合T3。然而，与两篇已发表的报告相反，人睾丸和肾α-2探针产物也未能结合T3。这些发现表明，高度保守的C末端37-40个残基对于c-erbA基因家族编码的蛋白质高亲和力结合T3很重要。
