Human endothelin-converting enzyme (ECE-1):: three isoforms with distinct subcellular localizations
Human endothelin-converting enzyme (ECE-1):: three isoforms with distinct subcellular localizations
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DOI：
10.1042/bj3280871
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发表时间：
1997-12-15
影响因子：
4.1
通讯作者：
Löffler, BM
中科院分区：
文献类型：
--
作者：
Schweizer, A;Valdenaire, O;Löffler, BM
内皮素转换酶 1 (ECE-1) 是一种膜结合金属蛋白酶，可催化无活性的大内皮素转化为活性内皮素。此前已鉴定出人类 ECE-1 的两种不同亚型（ECE-1a 和 ECE-1b）。在本研究中，我们克隆了一种新型人类 ECE-1 同工型，称为 ECE-1c，从而首次证明存在三种不同的 ECE-1 同工型。这三种亚型仅在 N 末端区域有所不同，并且通过使用替代启动子衍生自单个基因。核糖核酸酶保护实验表明，尽管人体组织之间三种异构体 mRNA 的相对水平有所不同，但 ECE-1c mRNA 通常是主要的异构体信使。免疫荧光显微镜分析显示三种亚型具有不同的亚细胞定位：ECE-1a 和 ECE-1c 位于细胞表面，而 ECE-1b 位于细胞内，并与跨高尔基体网络的标记蛋白显着共定位。我们确定这三种异构体在加工大内皮素 1 时具有相似的动力学速率常数（K-m、k(cat) 和 V-max），并且三种同工酶以相似的相对速度 1.0:0.1:0.1 裂解大内皮素异构体 1、2 和 3。
Endothelin-converting enzyme 1 (ECE-1) is a membrane-bound metalloprotease that catalyses the conversion of inactive big endothelins into active endothelins. Two different isoforms (ECE-1a and ECE-1b) have previously been identified for human ECE-1. In the present study we have cloned a novel human ECE-1 isoform, termed ECE-1c, and have thus shown for the first time the existence of three distinct ECE-1 isoforms. The three isoforms differ only in their N-terminal regions and are derived from a single gene through the use of alternative promoters. Ribonuclease protection experiments revealed that, although the relative levels of the three isoform mRNA species vary between human tissues, ECE-1c mRNA is generally the predominant isoform messenger. Immunofluorescence microscopy analysis showed distinct subcellular localizations for the three isoforms: whereas ECE-1a and ECE-1c are localized at the cell surface, ECE-1b was found to be intracellular and showed significant colocalization with a marker protein for the trans-Golgi network. We determined that the three isoforms have similar kinetic rate constants (K-m, k(cat) and V-max) for the processing of big endothelin 1 and that the big endothelin isoforms 1, 2 and 3 are cleaved with similar relative velocities of 1.0:0.1:0.1 by the three isoenzymes.