Beato M, Nieto A
Eur J Biochem. 1976 Apr 15;64(1):15-25. doi: 10.1111/j.1432-1033.1976.tb10270.x.
Uteroglobin, an hormonally induced protein composed of two similar subunits, represents around 50% of the proteins synthesized and secreted into the uterine lumen of rabbits treated sequentially with estradiol and progesterone. The endometrium of these animals was used as a source for the isolation of the mRNA for uteroglobin. Poly(A)-rich RNA, extracted from purified polysomes with phenol chloroform and isolated on oligo(dT)-cellulose columns, contains one fourth of the total protein coding activity of the endometrium. Between 20--25% of the polypeptides synthesized by this RNA in cell-free systems derived from Krebs II ascites cells or wheat germs react with a monospecific antiserum prepared in guinea pigs against uteroglobin. The material bound to the antibody was identified as a precursor of uteroglobin according to the following criteria. 1. The product synthesized in vitro can be displaced from the complex with the specific immunoglobulin by purified uteroglobin. 2. Analysis of the immunoprecipitate on polyacrylamide gels containing urea and dodecylsulfate demonstrate the existence of a single labelled polypeptide with an apparent molecular weight larger than the uteroglobin subunits. 3. The tryptic digest of this polypeptide, labelled in vitro with [3H]lysine, shares seven peptides with mature uteroglobin labelled with the same amino acid in perfused uteri, and exhibits and additional peptide not present in uteroglobin. 4. Injection of the same mRNA preparation into Xenopus oocytes results in the production of uteroglobin. The endometrium of intact animals treated with estradiol alone also contains the same mRNA bound to polysomes but in a smaller proportion, indicating that the progesterone-induced synthesis of uteroglobin is accompanied by an accumulation of the specific mRNA in the polysomes.
子宫珠蛋白是一种由两个相似亚基组成的激素诱导蛋白，在用雌二醇和孕酮顺序处理的兔子的子宫腔中合成并分泌的蛋白质中，它约占50%。这些动物的子宫内膜被用作分离子宫珠蛋白mRNA的来源。用苯酚氯仿从纯化的多核糖体中提取并在寡聚（dT）-纤维素柱上分离的富含多聚腺苷酸的RNA，含有子宫内膜总蛋白质编码活性的四分之一。在来自克雷布斯II腹水细胞或小麦胚芽的无细胞系统中，由这种RNA合成的多肽中有20% - 25%与豚鼠制备的抗子宫珠蛋白单特异性抗血清发生反应。根据以下标准，与抗体结合的物质被鉴定为子宫珠蛋白的前体。1. 体外合成的产物可以被纯化的子宫珠蛋白从与特异性免疫球蛋白的复合物中置换出来。2. 在含有尿素和十二烷基硫酸盐的聚丙烯酰胺凝胶上对免疫沉淀物进行分析，证明存在一种单一的标记多肽，其表观分子量大于子宫珠蛋白亚基。3. 用[3H]赖氨酸在体外标记的这种多肽的胰蛋白酶消化产物，与灌注子宫中用相同氨基酸标记的成熟子宫珠蛋白有七个相同的肽段，并且还显示出子宫珠蛋白中不存在的一个额外肽段。4. 将相同的mRNA制剂注射到非洲爪蟾卵母细胞中会导致子宫珠蛋白的产生。仅用雌二醇处理的完整动物的子宫内膜也含有与多核糖体结合的相同mRNA，但比例较小，这表明孕酮诱导的子宫珠蛋白合成伴随着特异性mRNA在多核糖体中的积累。
