Regulated cleavage-secretion of the membrane-bound angiotensin-converting enzyme.
Regulated cleavage-secretion of the membrane-bound angiotensin-converting enzyme.
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DOI：
10.1016/s0021-9258(17)42144-2
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发表时间：
1994-01
期刊：
影响因子：
--
通讯作者：
R. Ramchandran;G. Sen;K. Misono;I. Sen
中科院分区：
文献类型：
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作者：
R. Ramchandran;G. Sen;K. Misono;I. Sen
血管紧张素转换酶 (ACE) 是一种胞外蛋白，通过其羧基末端区域附近的疏水结构域锚定在质膜上。转染兔睾丸 ACE cDNA 的小鼠上皮细胞通过其膜锚定羧基末端区域的裂解加工合成、糖基化并分泌 ACE。由于裂解分泌过程缓慢，酶会积聚在细胞表面。我们表明，可以通过用促进肿瘤的佛波酯处理细胞来增强这一过程，从而导致细胞表面酶的消耗。裂解加工仅在蛋白质到达细胞表面后发生，并且不受高尔基体或溶酶体区室破坏的影响。通过对 ACE 分泌后留在细胞中的纯化 COOH 末端尾部的氨基末端残基和分泌的 ACE 的羧基末端残基进行测序，鉴定了确切的肽键裂解。裂解发生在 Arg-663 和 Ser-664 之间的一元位点处，产生可溶性酶并留下 74 个残基的细胞结合蛋白。这些结果证明了调节细胞结合 ACE 转化为可溶性酶的细胞机制的存在。
Angiotensin-converting enzyme (ACE) is an ectoprotein anchored in the plasma membrane through a hydrophobic domain near its carboxyl-terminal region. Mouse epithelial cells transfected with rabbit testicular ACE cDNA, synthesize, glycosylate, and secrete ACE by cleavage processing of its membrane-anchoring carboxyl-terminal region. Because the cleavage-secretion process is slow, the enzyme accumulates on the cell surface. We show that this process can be enhanced by treatment of cells with tumor-promoting phorbol esters leading to depletion of the cell surface enzyme. The cleavage processing occurs only after the protein has reached the cell surface and is not affected by disruption of the Golgi apparatus or the lysosomal compartments. The exact peptide bond cleaved has been identified by sequencing the amino-terminal residues of the purified COOH-terminal tail left in the cells after ACE is secreted and the carboxyl-terminal residues of secreted ACE. The cleavage occurs at a monobasic site between Arg-663 and Ser-664 generating the soluble enzyme and leaving a cell-bound protein of 74 residues. These results demonstrate the existence of cellular mechanisms that regulate the conversion of cell-bound ACE to a soluble enzyme.