Serum Amyloid P Component (SAP) Interactome in Human Plasma Containing Physiological Calcium Levels
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- 作者：Ebbe Toftgaard Poulsen ; Kata Wolff Pedersen ; Anna Maria Marzeda ; Jan J. Enghild
- 刊名：Biochemistry
- 出版年：2017
- 出版时间：February 14, 2017
- 年：2017
- 卷：56
- 期：6
- 页码：896-902
- 全文大小：310K
- ISSN：1520-4995
文摘
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 Ca2+ 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.