蛋白質A

蛋白質A(英語:Protein A)為金黃色葡萄球菌表面上發現的一種表面蛋白,大小約為42 kDa。該蛋白由 spa 基因轉譯而成,並由DNA的拓樸結構、包內滲透壓,以及一個名為ArlS-ArlR的雙單元調控系統英语two-component regulatory system調控。該蛋白可以與免疫球蛋白結合,故常用於生化研究。該蛋白三維構造中有五個同源性免疫球蛋白結合域,每個結合域都能與多種哺乳類的免疫球蛋白結合,最主要為IgG。蛋白質A能與大多數免疫球蛋白重鏈的Fc區域英语Fc region結合,甚至可與人類VH3蛋白質家族的Fab區域英语Fab region結合。當蛋白質A與免疫球蛋白結合後,這些免疫球蛋白便失去了作用,進而摧毀免疫系統的吞噬作用調理作用英语opsonization

Protein A
Protein A 1DEE 1L6X.png
Structure of a domain of protein A as a three-helix bundle binding to the heavy variable chain of a VH3 human Fab [1] left. Minimized protein A bound to Fc fragment of Rituximab.[2]
鑑定
標誌SpA
SCOP英语Structural Classification of Proteins1DEE / SUPFAM

參考文獻编辑

  1. ^ Graille M, Stura EA, Corper AL, Sutton BJ, Taussig MJ, Charbonnier JB, Silverman GJ. Crystal structure of a Staphylococcus aureus protein A domain complexed with the Fab fragment of a human IgM antibody: structural basis for recognition of B-cell receptors and superantigen activity. Proceedings of the National Academy of Sciences of the United States of America. May 2000, 97 (10): 5399–404. PMC 25840 . PMID 10805799. doi:10.1073/pnas.97.10.5399. 
  2. ^ Idusogie EE, Presta LG, Gazzano-Santoro H, Totpal K, Wong PY, Ultsch M, Meng YG, Mulkerrin MG. Mapping of the C1q binding site on rituxan, a chimeric antibody with a human IgG1 Fc. Journal of Immunology. April 2000, 164 (8): 4178–84. PMID 10754313. doi:10.4049/jimmunol.164.8.4178.