Polymorphisms A387P in thrombospondin-4 and N700S in thrombospondin-1 perturb calcium binding sites.
Polymorphisms A387P in thrombospondin-4 and N700S in thrombospondin-1 perturb calcium binding sites.
复制标题
血小板反应蛋白 4 中的 A387P 多态性和血小板反应蛋白 1 中的 N700S 多态性会扰乱钙结合位点。
DOI：
10.1096/fj.05-3712fje
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Plow,EdwardF
中科院分区：
文献类型：
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作者：
Stenina,OlgaI;Ustinov,Valentin;Krukovets,Irene;Marinic,Tina;Topol,EricJ;Plow,EdwardF
Recent genetic studies have associated members of the thrombospondin (TSP) gene family with premature cardiovascular disease. The disease‐associated polymorphisms lead to single amino acid changes in TSP‐4 (A387P) and TSP‐1 (N700S). These substitutions reside in adjacent domains of these highly homologous proteins. Secondary structural predictive programs and the homology of the domains harboring these amino acid substitutions to those in other proteins pointed to potential alterations of putative Ca2+binding sites that reside in close proximity to the polymorphic amino acids. Since Ca2+binding is critical for the structure and function of TSP family members, direct evidence for differences in Ca2+binding by the polymorphic forms was sought. Using synthetic peptides and purified recombinant variant fragments bearing the amino acid substitutions, we measured differences in Tb3+luminescence as an index of Ca2+binding. The Tb3+binding constants placed the TSP‐1 region affected by N700S polymorphism among other high‐affinity Ca2+binding sites. The affinity of Ca2+binding was lower for peptides (3.5‐fold) and recombinant fragments (10‐fold) containing the S700 vs. the N700 form. In TSP‐4, the P387 form acquired an additional Ca2+binding site absent in the A387 form. The results of our study suggest that both substitutions (A387P in TSP‐4 and N700S in TSP‐1) alter Ca2+binding properties. Since these substitutions exert the opposite effects on Ca2+binding, a decrease in TSP‐1 and an increase in TSP‐4, the two TSP variants are likely to influence cardiovascular functions in distinct but yet pathogenic ways.
