Autocatalytic cleavage of the EMR2 receptor occurs at a conserved G protein-coupled receptor proteolytic site motif
Autocatalytic cleavage of the EMR2 receptor occurs at a conserved G protein-coupled receptor proteolytic site motif
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DOI：
10.1074/jbc.m402974200
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发表时间：
2004-07-23
影响因子：
4.8
通讯作者：
Gordon, S
中科院分区：
文献类型：
--
作者：
Lin, HH;Chang, GW;Gordon, S
在G蛋白偶联受体蛋白水解位点（GPS）处的翻译后切割已经在许多B2类G蛋白偶联受体以及其他细胞表面蛋白如多囊蛋白-1中被证明。然而，GPS蛋白水解的机制从未被阐明。在这里，我们的特点是切割的人EMR 2受体，并确定了在GPS的蛋白水解过程的分子机制。在高度保守的His-Leu下箭头Ser（518）切割位点处的蛋白质水解可以发生在内质网隔室内部，导致两个蛋白质亚基以非共价方式缔合为异二聚体。P+1切割位点（Ser（518））的定点诱变显示，对于有效的蛋白水解，绝对需要Ser、Thr或Cys残基。将P-2 His残基替换为其他氨基酸产生缓慢加工的前体蛋白，其在限定的无细胞系统中自发水解。进一步的生物化学表征表明，GPS蛋白水解是介导的自催化分子内反应类似于所采用的N-末端亲核水解酶，这是已知的激活自己的自催化顺式蛋白水解。我们在这里提出，EMR 2的自蛋白水解裂解代表了其他GPS基序的蛋白质的范例，并建议这些GPS蛋白属于N-末端亲核水解酶的细胞表面受体亚家族。
Post-translational cleavage at the G protein-coupled receptor proteolytic site (GPS) has been demonstrated in many class B2 G protein-coupled receptors as well as other cell surface proteins such as polycystin-1. However, the mechanism of the GPS proteolysis has never been elucidated. Here we have characterized the cleavage of the human EMR2 receptor and identified the molecular mechanism of the proteolytic process at the GPS. Proteolysis at the highly conserved His-Leu down arrow Ser(518) cleavage site can occur inside the endoplasmic reticulum compartment, resulting in two protein subunits that associate noncovalently as a heterodimer. Site-directed mutagenesis of the P+1 cleavage site (Ser(518)) shows an absolute requirement of a Ser, Thr, or Cys residue for efficient proteolysis. Substitution of the P-2 His residue to other amino acids produces slow processing precursor proteins, which spontaneously hydrolyze in a defined cell-free system. Further biochemical characterization indicates that the GPS proteolysis is mediated by an autocatalytic intramolecular reaction similar to that employed by the N-terminal nucleophile hydrolases, which are known to activate themselves by self-catalyzed cis-proteolysis. We propose here that the autoproteolytic cleavage of EMR2 represents a paradigm for the other GPS motif-containing proteins and suggest that these GPS proteins belong to a cell surface receptor subfamily of N-terminal nucleophile hydrolases.