Schott D R, Shyamala G, Schneider W, Parry G
Division of Cell and Molecular Biology, University of California, Berkeley 94720.
Biochemistry. 1991 Jul 16;30(28):7014-20. doi: 10.1021/bi00242a029.
Progesterone receptors exist in two molecular forms commonly designated as "A" and "B" forms, the relative proportion of which can vary among species. In murine tissues, progesterone receptor exists predominantly as the "A" form which, in mammary glands, is also under developmental regulation [Shyamala et al. (1990) Endocrinology 126, 2882-2889]. Therefore, toward resolving the molecular mechanisms responsible for the predominance of the "A" form of progesterone receptor in murine tissues and its developmental regulation, we have isolated, sequenced, and expressed the complementary DNA corresponding to the mouse progesterone receptor. Nucleotide sequence analysis revealed two in-frame ATG codons, such that the largest open reading frame beginning with the first codon could encode a polypeptide with an estimated molecular weight of 99,089, while the shorter open reading frame beginning with the second codon could produce a polypeptide with a calculated molecular weight of 81,829. The murine progesterone receptor had complete identity for the DNA binding domain of human and rabbit progesterone receptors and 99% homology with the chicken progesterone receptor; for the steroid binding domain, it had 96% homology with human and rabbit progesterone receptors and 86% homology with chicken progesterone receptors. Expression of the complete complementary DNA in Chinese hamster ovary cells yielded a protein which bound the synthetic progestin promegestone with an equilibrium dissociation constant of approximately 1 nM, and in Western blot analyses revealed both "A" and "B" forms of immunoreactive receptor.
孕酮受体以两种分子形式存在，通常被称为“A”型和“B”型，其相对比例在不同物种间可能有所不同。在鼠类组织中，孕酮受体主要以“A”型存在，在乳腺中，它也受发育调控[Shyamala等人（1990年），《内分泌学》126卷，2882 - 2889页]。因此，为了阐明鼠类组织中孕酮受体“A”型占主导地位及其发育调控的分子机制，我们分离、测序并表达了与小鼠孕酮受体相对应的互补DNA。核苷酸序列分析揭示了两个读码框内的ATG密码子，这样，从第一个密码子开始的最大开放阅读框可编码一个估计分子量为99,089的多肽，而从第二个密码子开始的较短开放阅读框可产生一个计算分子量为81,829的多肽。小鼠孕酮受体与人及兔孕酮受体的DNA结合结构域完全相同，与鸡孕酮受体有99%的同源性；对于类固醇结合结构域，它与人及兔孕酮受体有96%的同源性，与鸡孕酮受体有86%的同源性。在中国仓鼠卵巢细胞中表达完整的互补DNA产生了一种蛋白质，该蛋白质与合成孕激素普美孕酮结合，平衡解离常数约为1 nM，在蛋白质免疫印迹分析中显示出免疫反应性受体的“A”型和“B”型。
