An 18-kDa androgen-regulated protein that modifies galactosyltransferase activity is synthesized by the rat caput epididymidis, but has no structural similarity to rat milk alphalactalbumin.
An 18-kDa androgen-regulated protein that modifies galactosyltransferase activity is synthesized by the rat caput epididymidis, but has no structural similarity to rat milk alphalactalbumin.
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一种可修饰半乳糖基转移酶活性的 18 kDa 雄激素调节蛋白由大鼠附睾合成，但与大鼠乳汁 α-乳白蛋白没有结构相似性。
DOI：
10.1095/biolreprod43.3.497
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发表时间：
1990
影响因子：
3.6
通讯作者：
Hamilton,DW
中科院分区：
文献类型：
--
作者：
Moore,A;Hall,L;Hamilton,DW
据报道，半乳糖基转移酶和α-乳白蛋白样活性存在于男性生殖道的睾丸后液中。在泌乳乳腺中，这些活性构成了乳糖合成酶复合物。先前报道的动力学参数和受体特异性以及最近的氨基酸序列分析反对乳腺和附睾活动是同一基因的产物。在本文中，我们提出了大鼠附睾 mRNA 的无细胞翻译以及附睾 mRNA 与真实大鼠 α-乳清蛋白 cDNA 杂交的 Northern 印迹分析，支持了这种同一性的缺乏，并描述了所谓的大鼠附睾 α-乳清蛋白样复合物的雄激素调节的 18 kDa 成分沿附睾长度的差异合成和分泌。我们得出的结论是，虽然所谓的附睾α乳清蛋白部分（EuL&）的18 kDa成分能够与许多不相关的分子一样，在体外调节半乳糖基转移酶受体特异性，但它与真实的大鼠乳腺α乳清蛋白之间不存在主要结构相似性。鉴于 EaIA 的活性仅为纯牛奶 α-乳白蛋白的 100 倍，我们认为它可能不具有生理重要性，并且半乳糖基转移酶活性的修饰可能不是 18 kDa 分子的功能。
Galactosyltransferase and alphalactalbumin-like activities have been reported to be present in the post-testicular fluids of the male reproductive tract In the lactating mammary gland, these activities constitute the lactose synthetase complex. Kinetic parameters and acceptor specilicities previously reported, along with recent amino acid sequence analysis argue against the mammary gland and epididymal activities being products of the same gene. In this paper we present cell-free translation of rat epididymal mRNA and Northern blot analysis of epididymal mRNA hybridized with authentic rat a-lactalbumin cDNA supporting this lack of identity and describe the differential synthesis and secretion of the androgen-regulated 18 kDa component of the socalled rat epididymal alphalactalbumin-like complex along the length of the epididymis. We conclude that although the 18 kDa component of the so-called epididymal alphalactalbumin moiety (EuL&) is capable, in common with a number of unrelated molecules, of modilting galactosyltransferase acceptor specificity in vitro, there is no primary structural similarity between it and authentic rat mammary alphalactalbumin. In view of the fact that the activity of EaIA is j/100th that of authentic milk alphalactalbumin, we suggest that it may not be of physiological importance and that modification of galactosyltransferase activity may not be the function of the 18 kDa molecule.