蛋白质A

可與免疫球蛋白結合的表面蛋白

蛋白质A(英语:Protein A)为金黄色葡萄球菌表面上发现的一种表面蛋白,大小约为42 kDa。该蛋白由 spa 基因转译而成,并由DNA的拓朴结构、包内渗透压,以及一个名为ArlS-ArlR的双单元调控系统英语two-component regulatory system调控。该蛋白可以与免疫球蛋白结合,故常用于生化研究。该蛋白三维构造中有五个同源性免疫球蛋白结合域,每个结合域都能与多种哺乳类的免疫球蛋白结合,最主要为IgG。蛋白质A能与大多数免疫球蛋白重链的Fc区域英语Fc region结合,甚至可与人类VH3蛋白质家族的Fab区域英语Fab region结合。当蛋白质A与免疫球蛋白结合后,这些免疫球蛋白便失去了作用,进而摧毁免疫系统的吞噬作用调理作用英语opsonization

Protein A
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]
鉴定
标志SpA
SCOP英语Structural Classification of Proteins1DEE / SUPFAM

参考文献

  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.