Ultrastructural localization of angiotensin I-converting enzyme (EC 3.4.15.1) and neutral metalloendopeptidase (EC 3.4.24.11) in the proximal tubule of the human kidney.
Ultrastructural localization of angiotensin I-converting enzyme (EC 3.4.15.1) and neutral metalloendopeptidase (EC 3.4.24.11) in the proximal tubule of the human kidney.
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发表时间：
1988-12
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通讯作者：
Schulz Ww;H. Hagler;L. Buja;Erdös Eg
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作者：
Schulz Ww;H. Hagler;L. Buja;Erdös Eg
我们研究了血管紧张素转换酶(ACE)和中性金属内肽酶24.11(NEP)这两种参与调节肽加工的酶在人肾脏中的位置和相对浓度。针对这些纯化的人类肾脏酶产生的抗体被用来通过免疫金标法确定它们的超微结构分布。对固定的人肾超薄冰冻切片进行免疫细胞化学染色。这两种酶均定位于刷状缘质膜外，少量分布于近端小管上皮细胞顶端的囊泡细胞器中。此外，在基底内折叠处还检测到中等数量的NEP和一些ACE。远端肾小管内未见NEP和ACE。近端肾小管上皮细胞刷缘的金颗粒用计算机形态计量学系统定量。结果表明，在抗血清浓度下，NEP和ACE在刷子边缘可获得的抗原位点数目大致相同，从而产生最佳标记。ACE和NEP在近端肾小管上皮刷缘膜上的显著定位提示，近端肾小管上皮细胞中的这两种酶参与了肾小球滤过后血浆衍生肽的裂解。
We investigated the location and relative concentration in the human kidney of two enzymes involved in the processing of regulatory peptides, i.e., the angiotensin I-converting enzyme (ACE) and the neutral metalloendopeptidase 24.11 (NEP). Antibodies raised against these purified human kidney enzymes were used to determine their ultrastructural distribution by the immunogold procedure. Immunocytochemistry was performed on ultrathin frozen sections of fixed human kidney. Both enzymes were localized on the outside of the brush-border plasma membrane and, to a lesser extent, in vesicular organelles in the apical regions of epithelial cells in the proximal tubules. In addition, moderate amounts of NEP and some ACE were detected on the basal infoldings. No NEP or ACE was found in the distal tubules. Gold particles on the brush-border of proximal tubular epithelial cells were quantified with a computer based morphometry system. The results indicated about equal numbers of accessible antigenic sites for NEP and ACE on the brush-border at concentrations of antisera which yielded optimal labeling. The prominent localization of ACE and NEP on the brush-border membranes of proximal tubular epithelium suggests that these enzymes in the proximal tubules are involved in the cleavage of plasma-derived peptides after glomerular filtration.