Schwartz H L, Lazar M A, Oppenheimer J H
Department of Medicine, University of Minnesota, Minneapolis 55455.
J Biol Chem. 1994 Oct 7;269(40):24777-82.
Messenger RNA for thyroid hormone receptor (TR) isoforms alpha 1 and beta 1 are widely distributed in rat tissues. Until recently, TR beta 2 mRNA was believed to be limited to the pituitary and the assumption was made that TR beta 2 protein was similarly restricted. We determined the distribution of TR beta 2 protein in selected adult and fetal rat tissues using three anti-TR beta 2 antisera directed to different amino acid sequences of the distinctive A/B domain of TR beta 2. The proportion of total nuclear binding capacity cleared by each antiserum was determined by saturation analysis. 10-20% of total binding capacity in adult brain, liver, kidney, and heart was immunoprecipitated by each antiserum. Use of specific antibodies to TR beta 1 and TR alpha 1 showed these isoforms accounted for the remainder of total T3 binding. Fetal liver and brain, however, contained only TR alpha 1. Immunohistochemical analysis of the adult tissues showed TR beta 2 present in nuclei. Reverse transcription polymerase chain reaction detected low levels of TR beta 2 mRNA in the adult tissues. We infer that TR beta 2 accounts for a significant fraction of TR in adult rat tissues despite the low levels of its mRNA.
甲状腺激素受体（TR）亚型α1和β1的信使核糖核酸在大鼠组织中广泛分布。直到最近，人们还认为TRβ2信使核糖核酸仅限于垂体，并且推测TRβ2蛋白也有类似的分布限制。我们使用三种针对TRβ2独特A/B结构域不同氨基酸序列的抗TRβ2抗血清，确定了成年和胎鼠选定组织中TRβ2蛋白的分布。通过饱和分析确定每种抗血清清除的总核结合能力的比例。每种抗血清免疫沉淀成年脑、肝、肾和心脏中总结合能力的10 - 20%。使用针对TRβ1和TRα1的特异性抗体表明，这些亚型占总T3结合的其余部分。然而，胎肝和胎脑中仅含有TRα1。对成年组织的免疫组织化学分析显示TRβ2存在于细胞核中。逆转录聚合酶链反应在成年组织中检测到低水平的TRβ2信使核糖核酸。我们推断，尽管TRβ2信使核糖核酸水平较低，但它在成年大鼠组织的TR中占很大比例。
