Poulsen Ebbe Toftgaard, Pedersen Kata Wolff, Marzeda Anna Maria, Enghild Jan J
Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University , Gustav Wieds Vej 10, Aarhus, Denmark.
Biochemistry. 2017 Feb 14;56(6):896-902. doi: 10.1021/acs.biochem.6b01027. Epub 2017 Feb 1.
The pentraxin serum amyloid P component (SAP) is secreted by the liver and found in plasma at a concentration of approximately 30 mg/L. SAP is a 25 kDa homopentamer known to bind both protein and nonprotein ligands, all in a calcium-dependent manner. The function of SAP is unclear but likely involves the humoral innate immune system spanning the complement system, inflammation, and coagulation. Also, SAP is known to bind to the generic structure of amyloid deposits and possibly to protect them against proteolysis. In this study, we have characterized the SAP interactome in human plasma containing the physiological Ca concentration using SAP affinity pull-down and co-immunoprecipitation experiments followed by mass spectrometry analyses. The analyses resulted in the identification of 33 proteins, of which 24 were direct or indirect interaction partners not previously reported. The SAP interactome can be divided into categories that include apolipoproteins, the complement system, coagulation, and proteolytic regulation.
五聚体血清淀粉样蛋白P成分（SAP）由肝脏分泌，在血浆中的浓度约为30 mg/L。SAP是一种25 kDa的同五聚体，已知能以钙依赖的方式结合蛋白质和非蛋白质配体。SAP的功能尚不清楚，但可能涉及跨越补体系统、炎症和凝血的体液固有免疫系统。此外，已知SAP能结合淀粉样沉积物的一般结构，并可能保护它们免受蛋白水解。在本研究中，我们利用SAP亲和下拉和共免疫沉淀实验，随后进行质谱分析，对含有生理钙浓度的人血浆中的SAP相互作用组进行了表征。分析结果鉴定出33种蛋白质，其中24种是以前未报道的直接或间接相互作用伙伴。SAP相互作用组可分为载脂蛋白、补体系统、凝血和蛋白水解调节等类别。
