Angiotensin II-binding protein in adult and neonatal rat heart.
Angiotensin II-binding protein in adult and neonatal rat heart.
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成年和新生大鼠心脏中的血管紧张素 II 结合蛋白。
DOI：
10.1016/0022-2828(91)90048-q
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发表时间：
1991
影响因子：
5
通讯作者：
Rajasekaran,AK
中科院分区：
文献类型：
--
作者：
Sen,I;Rajasekaran,AK
在成年大鼠肾上腺、肾、肝、心和脑的100 000× g上清液组分中鉴定出血管紧张素II结合活性。这种结合对血管紧张素II是特异性的;它具有高亲和力，完全依赖于有机汞、对氯汞苯磺酸的存在。另一方面，还原剂引起结合配体的解离。[125 I]-血管紧张素II与大鼠心脏可溶性组分共价交联，SDS-聚丙烯酰胺凝胶电泳和放射自显影表明，与血管紧张素II结合的大分子很可能是表观质量为78000道尔顿的蛋白质。血管紧张素II与100 000× g新生儿和新生儿上清组分结合的比较（1-3日龄）和成年（3个月大）大鼠心脏显示，血管紧张素II以相似的亲和力和特异性结合，但新生儿心脏的结合位点数量要高出3倍（KD和B max成人分别为10.4±3.1 nm和1.6±0.4 pmol/mg蛋白，新生儿分别为8.8±2.9 nm和4.9±0.7 pmol/mg蛋白）。从新生大鼠心脏制备的膜级分类似地以可饱和的方式结合血管紧张素II，并且具有高亲和力（KD 4.3±0.5 nm和B max 146.4±4.9 fmol/mg蛋白），但是从成年大鼠心脏制备的类似的膜级分没有显示任何血管紧张素II结合。这些观察结果表明，在大鼠心脏，有一个减少血管紧张素II结合位点，可溶性和膜结合，随着年龄的增长。因此，大鼠心脏，在不同的发展阶段，从它制备的心肌细胞应该提供一个合适的系统，研究血管紧张素II结合蛋白的发育调节。
An angiotensin II-binding activity has been identified in the 100 000× g supernatant fraction of adrenal gland, kidney, liver, heart and brain of adult rat. The binding is specific for angiotensin II; it is of high affinity and completely dependent upon the presence of an organomercurial, p-chloromercuriphenylsulfonic acid. Reducing agents, on the other hand, cause a dissociation of bound ligand. Covalent cross-linking of [125 I]-angiotensin II to the soluble fraction from rat heart followed by SDS-polyacrylamide gel electrophoresis and autoradiography indicated that the macromolecule that binds angiotensin II is most probably a protein with an apparent mass of 78 000 dalton. A comparison of the binding of angiotensin II to the 100 000× g supernatant fraction from both neonatal (1–3-day-old) and adult (3-month-old) rat hearts revealed that angiotensin II binds with similar affinity and specificity, but the number of binding sites is 3-fold higher in the neonatal heart (K D and B max were 10.4±3.1 n m and 1.6±0.4 pmol/mg protein for adult and 8.8±2.9 n m and 4.9±0.7 pmol/mg protein for neonatal heart, respectively). The membrane fraction prepared from neonatal rat heart similarly bound angiotensin II in a saturable manner and with high affinity (K D 4.3±0.5 n m and B max 146.4±4.9 fmol/mg protein), but a similar membrane fraction prepared from adult rat heart failed to show any angiotensin II binding. These observations indicated that, in rat heart, there is a decrease of angiotensin II-binding sites, both soluble and membrane bound, with age. Hence, rat heart, at various stages of development, and myocytes prepared from it should provide a suitable system with which to study the developmental regulation of the angiotensin II-binding protein.