人凝血因子IX的首个表皮生长因子样结构域含有一个高亲和力钙结合位点。
The first EGF-like domain from human factor IX contains a high-affinity calcium binding site.
作者信息
Handford P A, Baron M, Mayhew M, Willis A, Beesley T, Brownlee G G, Campbell I D
机构信息
Sir William Dunn School of Pathology, University of Oxford, UK.
出版信息
EMBO J. 1990 Feb;9(2):475-80. doi: 10.1002/j.1460-2075.1990.tb08133.x.
It has been suggested that epidermal growth factor-like (EGF-like) domains, containing conserved carboxylate residues, are responsible for the high-affinity calcium binding exhibited by a number of vitamin K-dependent plasma proteins involved in the control of the blood coagulation cascade. These include the procoagulant factors IX and X, and the anticoagulants protein C and protein S. To test this hypothesis we have expressed the first EGF-like domain from human factor IX (residues 46-84) using a yeast secretion system, and examined calcium binding to the domain. Using 1H-NMR to measure a calcium-dependent shift assigned to Tyr69 we have detected a high-affinity calcium binding site (Kd = 200-300 microM). We suggest that other EGF-like domains of this type may have similar calcium binding properties. In addition, we have completely assigned the aromatic region of the NMR spectrum by NOESY and COSY analysis, and have used these data to discuss the effect of calcium and pH on the conformation of the domain with reference to a model based on the structure of human EGF.
有人提出，含有保守羧酸盐残基的表皮生长因子样（EGF样）结构域，是一些参与血液凝固级联控制的维生素K依赖性血浆蛋白表现出高亲和力钙结合的原因。这些蛋白包括促凝血因子IX和X，以及抗凝血蛋白C和蛋白S。为了验证这一假设，我们使用酵母分泌系统表达了人因子IX的第一个EGF样结构域（第46 - 84位氨基酸残基），并检测了该结构域与钙的结合情况。利用1H - NMR测量归属于Tyr69的钙依赖性位移，我们检测到一个高亲和力钙结合位点（解离常数Kd = 200 - 300 microM）。我们认为这种类型的其他EGF样结构域可能具有类似的钙结合特性。此外，我们通过NOESY和COSY分析完全确定了NMR谱的芳香区，并利用这些数据，参照基于人EGF结构的模型，讨论了钙和pH对该结构域构象的影响。
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