Cloning of a cDNA encoding an ectoenzyme that degrades thyrotropin-releasing hormone.
Cloning of a cDNA encoding an ectoenzyme that degrades thyrotropin-releasing hormone.
复制标题
编码降解促甲状腺素释放激素的胞外酶的 cDNA 的克隆。
DOI：
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发表时间：
1994
影响因子：
11.1
通讯作者：
K. Bauer
中科院分区：
文献类型：
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作者：
B. Schauder;L. Schomburg;J. Köhrle;K. Bauer
促甲状腺激素释放激素（Thyrotropin-releasing hormone，TRH）是一种重要的细胞外信号物质，是下丘脑释放因子，刺激腺垂体激素的释放，在中枢和外周神经系统中起神经递质/神经调质的作用。TRH释放后的失活是由一种胞外酶催化的，该酶优先定位于脑中的神经元细胞和催乳垂体细胞上。这种酶表现出非常高的底物特异性以及其他不寻常的性质。腺垂体酶的活性受到雌二醇和甲状腺激素的严格控制，表明这种酶本身可能具有调节功能。从大鼠或猪脑中分离的酶片段通过酶消化或溴化氰裂解产生，通过反相HPLC纯化，并测序。PCR扩增和筛选的cDNA文库，从大鼠脑和垂体的鉴定和分离的cDNA编码的蛋白质的1025个氨基酸。推导的氨基酸序列的分析是一致的，作为一个糖基化的，膜锚定的锌金属肽酶的酶的鉴定。此外，北方印迹分析表明，mRNA水平的组织分布的酶和在垂体组织中的转录水平迅速增加时，动物与三碘甲状腺原氨酸治疗。最后，瞬时转染COS-7细胞与此cDNA导致的活性外肽酶的表达，显示TRH降解ectoenzyme的特性。
Thyrotropin-releasing hormone (TRH) is an important extracellular signal substance that acts as a hypothalamic-releasing factor, which stimulates the release of adenohypophyseal hormones and functions as a neurotransmitter/neuromodulator in the central and peripheral nervous system. The inactivation of TRH after its release is catalyzed by an ectoenzyme localized preferentially on neuronal cells in the brain and on lactotrophic pituitary cells. This enzyme exhibits a very high degree of substrate specificity as well as other unusual properties. The activity of the adenohypophyseal enzyme is stringently controlled by estradiol and thyroid hormones, indicating that this enzyme itself may serve regulatory functions. Fragments of the enzyme isolated from rat or pig brain were generated by enzymatic digestion or cyanogen bromide cleavage, purified by reverse-phase HPLC, and sequenced. PCR amplification and screening of cDNA libraries from rat brain and pituitary led to the identification and isolation of a cDNA that encodes a protein of 1025 amino acids. The analysis of the deduced amino acid sequence was consistent with the identification of the enzyme as a glycosylated, membrane-anchored Zn metallopeptidase. Furthermore, Northern blot analysis demonstrated that the mRNA levels paralleled the tissue distribution of the enzyme and that in pituitary tissue the transcript levels rapidly increased when the animals were treated with triiodothyronine. Finally, transient transfection of COS-7 cells with this cDNA led to the expression of an active ectopeptidase that displayed the characteristics of the TRH-degrading ectoenzyme.