Vanmontfort D, Fidler A E, Heath D A, Lawrence S B, Tisdall D J, Greenwood P J, McNatty K P
AgResearch Wallaceville, Upper Hutt, New Zealand.
J Mol Endocrinol. 1998 Oct;21(2):141-52. doi: 10.1677/jme.0.0210141.
An inhibin alpha-subunit cDNA sequence from the Australian brushtail possum (Trichosurus vulpecula) has been identified and analysed. The cDNA includes an open reading frame encoding a predicted precursor protein of 361 amino acids. The predicted protein sequence includes four possible proteolytic cleavage sites, 12 evolutionarily conserved cysteine residues and three potential N-linked glycosylation sites. The mature alpha-subunit is the carboxyl terminal fragment (alphaC) consisting of 131 amino acids. The full-length precursor protein shows a mean identity with eutherian homologues of 69.8%. The homology is not evenly distributed, with the putative alphaC fragment showing the highest level (79.7%). Using Northern hybridisation, an alpha-subunit transcript of approximately 1.6 kb was detected in adult possum ovary. Using in situ hybridisation and immunocytochemistry, inhibin alpha-subunit was localised exclusively to the granulosa cell layers of follicles. Hybridisation and immunostaining for the inhibin alpha-subunit were first observed in granulosa cells of primary follicles and the expression continued throughout all stages of follicular growth. Inhibin alpha-subunit mRNA and protein were also detected in cells of the corpus luteum. In summary, results indicate considerable conservation of the structure and possible function of the inhibin alpha-subunit protein since the divergence of the marsupial and eutherian mammalian lineages. The expression data suggest that, in the adult possum, inhibin may have a role in ovarian follicular growth from the primary stage of development.
已鉴定并分析了来自澳大利亚帚尾袋貂（Trichosurus vulpecula）的抑制素α亚基cDNA序列。该cDNA包含一个开放阅读框，编码一个预测的由361个氨基酸组成的前体蛋白。预测的蛋白质序列包括四个可能的蛋白水解切割位点、12个进化上保守的半胱氨酸残基和三个潜在的N-连接糖基化位点。成熟的α亚基是由131个氨基酸组成的羧基末端片段（αC）。全长前体蛋白与真兽亚纲同源物的平均一致性为69.8%。这种同源性分布不均，假定的αC片段显示出最高水平（79.7%）。使用Northern杂交，在成年袋貂卵巢中检测到一个约1.6 kb的α亚基转录本。使用原位杂交和免疫细胞化学方法，抑制素α亚基仅定位于卵泡的颗粒细胞层。抑制素α亚基的杂交和免疫染色首先在初级卵泡的颗粒细胞中观察到，并且在卵泡生长的所有阶段都持续表达。在黄体细胞中也检测到了抑制素α亚基的mRNA和蛋白质。总之，结果表明自有袋类和真兽类哺乳动物谱系分化以来，抑制素α亚基蛋白的结构和可能的功能具有相当程度的保守性。表达数据表明，在成年袋貂中，抑制素可能在卵泡发育的初级阶段对卵巢卵泡生长起作用。
