Differences in the activation mechanism between the α and β subunits of human meprin
Differences in the activation mechanism between the α and β subunits of human meprin
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DOI：
10.1515/bc.2003.092
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发表时间：
2003-05-01
影响因子：
3.7
通讯作者：
Stöcker, W
中科院分区：
文献类型：
--
作者：
Becker, C;Kruse, MN;Stöcker, W
meprin是astacin家族的锌内肽酶，其在小鼠、大鼠和人的肾和肠刷状缘膜中以膜结合或分泌形式表达。有两种类型的meprin亚基，α和β，其形成二硫键结合的同源和异源二聚体;进一步的寡聚化由非共价相互作用介导。这两个亚基都被翻译为必须通过去除N-末端前肽来激活的酶原。在肠道中，最可能的激活剂是胰蛋白酶。此外，纤溶酶已被证明激活结肠直肠癌组织中的人α亚基。在本研究中，我们在杆状病毒感染的昆虫细胞中过表达了人meprin a亚基和带有His标签的meprin 13可溶性尾部开关突变体。通过凝胶过滤和亲和层析纯化重组同源寡聚蛋白，产率高达10 mg/l细胞培养基，并分析其活化机制。虽然α和β同源寡聚体都被胰蛋白酶激活，但只有甲氧苄氨嘧啶α同源寡聚体被纤溶酶加工成其成熟形式。这些结果表明，不同的可及性的前肽在meprin同源寡聚体，并提出了一个解释的外观meprin异源寡聚体组成的活性α，但潜在的β亚基。
Meprins are zinc-endopeptidases of the astacin family, which are expressed as membrane-bound or secreted forms in renal and intestinal brush-border membranes of mouse, rat and man. There are two types of meprin subunits, alpha and beta, which form disulfide-bonded homo- and heterodimers; further oligomerization is mediated by non-covalent interactions. Both subunits are translated as proenzymes that have to be activated by removal of an N-terminal propeptide. In the gut, the most probable activator is trypsin. In addition, plasmin has been shown to activate the human alpha subunit in colorectal cancer tissue. In the present study we have overexpressed the human meprin a subunit and a His-tagged soluble tail-switch-mutant of meprin 13 in Baculovirus-infected insect cells. The recombinant homo-oligomeric proteins were purified by gel filtration and affinity chromatography with yields of up to 10 mg/l cell culture medium and analyzed with regard to their activation mechanism. While both alpha and beta homo-oligomers are activated by trypsin, only meprin alpha homo-oligomers are processed to their mature form by plasmin. These results indicate a different accessibility of the propeptide in meprin homo-oligomers and suggest an explanation for the appearance of meprin hetero-oligomers consisting of active alpha, but latent beta subunits.