The Kell protein of the common K2 phenotype is a catalytically active metalloprotease, whereas the rare Kell K1 antigen is inactive -: Identification of novel substrates for the Kell protein
The Kell protein of the common K2 phenotype is a catalytically active metalloprotease, whereas the rare Kell K1 antigen is inactive -: Identification of novel substrates for the Kell protein
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DOI：
10.1074/jbc.m500100200
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发表时间：
2005-06-03
影响因子：
4.8
通讯作者：
Ouimet, T
中科院分区：
文献类型：
--
作者：
Clapéron, A;Rose, C;Ouimet, T
Kell 血型是一个高度多态性系统，包含由 Kell 蛋白携带的 20 多种不同抗原，Kell 是一种 93 kDa II 型糖蛋白，与锌依赖性金属蛋白酶 M13 家族的成员表现出高度序列同源性，其典型成员是脑啡肽酶。 Kell K1 是一种在 9% 的白种人群体中表达的抗原，其特征是 Kell K2 抗原的点突变 (T193M)，并且位于假定的 N-糖基化共有序列内。最近，Kell 的重组、非生理、可溶形式被证明可以裂解 Big ET-3，产生成熟的血管收缩肽。为了更好地表征 Kell 蛋白的酶活性以及影响翻译后加工的抗原点突变所引入的可能差异，Kell K1 和 Kell K2 抗原的膜结合形式在 K562 细胞（红系细胞系）或 HEK293 细胞（非红系系统）中表达，及其药理学特征和酶特异性 评估了合成和天然肽。本文提供的结果表明，两种抗原在其酶活性方面具有相当大的差异，尽管其运输模式没有差异。事实上，虽然两种抗原都在细胞表面表达，但 Kell K1 蛋白显示出无活性，而 Kell K2 抗原以高亲和力结合中性溶酶抑制性化合物，如磷酰胺和噻吩，裂解内皮素肽的前体，并灭活速激肽家族的成员，其酶特性与速激肽家族其他成员相似。 它所属的金属蛋白酶 M13 家族。
Kell blood group is a highly polymorphic system containing over 20 different antigens borne by the protein Kell, a 93-kDa type II glycoprotein that displays high sequence homology with members of the M13 family of zinc-dependent metalloproteases whose prototypical member is neprilysin. Kell K1 is an antigen expressed in 9% of the Caucasian population, characterized by a point mutation (T193M) of the Kell K2 antigen, and located within a putative N-glycosylation consensus sequence. Recently, a recombinant, non-physiological, soluble form of Kell was shown to cleave Big ET-3 to produce the mature vasoconstrictive peptide. To better characterize the enzymatic activity of the Kell protein and the possible differences introduced by antigenic point mutations affecting post-translational processing, the membrane-bound forms of the Kell K1 and Kell K2 antigens were expressed either in K562 cells, an erythroid cell line, or in HEK293 cells, a non-erythroid system, and their pharmacological profiles and enzymatic specificities toward synthetic and natural peptides were evaluated. Results presented herein reveal that the two antigens possess considerable differences in their enzymatic activities, although not in their trafficking pattern. Indeed, although both antigens are expressed at the cell surface, Kell K1 protein is shown to be inactive, whereas the Kell K2 antigen binds neprilysin inhibitory compounds such as phosphoramidon and thiorphan with high affinity, cleaves the precursors of the endothelin peptides, and inactivates members of the tachykinin family with enzymatic properties resembling those of other members of the M13 family of metalloproteases to which it belongs.