A 13-kilodalton protein purified from milk fat globule membranes is closely related to a mammary-derived growth inhibitor.
A 13-kilodalton protein purified from milk fat globule membranes is closely related to a mammary-derived growth inhibitor.
复制标题
从乳脂肪球膜中纯化的 13 千道尔顿蛋白质与乳腺生长抑制剂密切相关。
作者：
R. Brandt;M. Pepperle;A. Otto;R. Kraft;F. Boehmer;R. Grosse
使用特异性抗体对抗先前纯化的[Boehmer， f . d .]陈晓明，陈晓明，陈晓明，等（1984）乳腺源性生长抑制因子（MDGI）的研究进展[j]。，卡夫，R.，奥托，A.，温特施泰特，C.，赫尔曼，U.，库尔茨，A.，穆勒，T.，罗德，K., Etzold， G.，莱曼，W.，兰根，P.，赫尔丁，C.- h。（1987） J. Biol。[化学，262,15137-15143]，测定了13千道尔顿（kDa）抗原在不同组分牛奶中的定位和相对量。乳脂球膜（MFGM）抗原含量最高。斑点免疫结合试验显示，随着产后哺乳期的开始，牛和人的mfgm相关抗原的免疫反应量急剧增加。这一发现与MDGI早期获得的数据相一致，表明乳腺上皮细胞的增殖状态与免疫反应性抗原的数量之间存在关系。通过制备十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和电洗脱，从MFGM中纯化出13kda抗原。mfgm衍生的13-kDa多肽与MDGI几乎相同，通过胰蛋白酶消化和部分氨基酸序列分析证实了这两种蛋白质。结果清楚地表明存在一种膜结合mdgi相关的13-kDa蛋白，从而支持膜相关生长抑制剂可能参与乳腺上皮细胞的生长调节。
With the use of specific antibodies against a previously purified [Boehmer, F.-D., Lehmann, W., Schmidt, H., Lange, P., & Grosse, R. (1984) Exp. Cell Res. 150, 466-477] and sequenced mammary-derived growth inhibitor (MDGI) [Boehmer, F.-D., Kraft, R., Otto, A., Wernstedt, C., Hellmann, U., Kurtz, A., Mueller, T., Rohde, K., Etzold, G., Lehmann, W., Langen, P., Heldin, C.-H., & Grosse, R. (1987) J. Biol. Chem. 262, 15137-15143], the localization and relative amount of immunoreactive 13-kilodalton (kDa) antigen in different fractions of bovine milk were determined. The highest amount of antigen was found to be associated with the milk fat globule membranes (MFGM). As revealed by a dot immunobinding assay, the amount of immunoreactive bovine and human MFGM-associated antigen increased dramatically with the onset of lactation after delivery. This finding corresponds to earlier data obtained for MDGI and indicates a relationship between the proliferative state of mammary epithelial cells and the amount of immunoreactive antigen. The 13-kDa antigen has been purified from MFGM to homogeneity by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electroelution. The MFGM-derived 13-kDa polypeptide was found to be almost identical with MDGI as demonstrated by tryptic digestion and partial amino acid sequence analysis of tryptic fragments of both proteins. The results clearly show the presence of a membrane-bound MDGI-related 13-kDa protein, thus supporting the possible involvement of membrane-associated growth inhibitors in growth regulation of mammary epithelial cells.