Malhotra R, Haurum J S, Thiel S, Sim R B
Department of Biochemistry, University of Oxford, U.K.
Biochem J. 1994 Dec 1;304 ( Pt 2)(Pt 2):455-61. doi: 10.1042/bj3040455.
Collectins are a group of soluble proteins each of which has collagenous domains and non-collagenous globular domains, the latter containing the consensus residues found in C-type lectins. Members of the collectin family are the serum proteins mannan-binding protein (MBP), conglutinin, CL-43, and the lung-associated proteins surfactant protein A (SP-A) and surfactant protein D (SP-D). MBP and conglutinin have been shown previously to bind to influenza viruses and to inhibit the infectivity and haemagglutinating activity of influenza viruses. We report here that the lung protein SP-A, like MBP, can bind to influenza virus (strain A/X31) through its lectin domain and inhibit the virus-mediated agglutination of red cells. The binding of SP-A or MBP to influenza virus was saturable, concentration-dependent, and required the presence of Ca2+ ions. Ligand-blot analysis, using MBP as ligand, of the virus lysate indicated that MBP binds to a 68 kDa viral species. The 68 kDa species was isolated to homogeneity and was shown to be the viral neuraminidase. The purified 68 kDa species inhibited the binding of both MBP and SP-A to influenza virus.
凝集素是一类可溶性蛋白质，每一种都具有胶原结构域和非胶原球状结构域，后者含有C型凝集素中发现的共有残基。凝集素家族的成员包括血清蛋白甘露糖结合蛋白（MBP）、共凝集素、CL-43，以及与肺相关的蛋白表面活性蛋白A（SP-A）和表面活性蛋白D（SP-D）。先前已表明MBP和共凝集素可与流感病毒结合，并抑制流感病毒的感染性和血凝活性。我们在此报告，肺蛋白SP-A与MBP一样，可通过其凝集素结构域与流感病毒（A/X31株）结合，并抑制病毒介导的红细胞凝集。SP-A或MBP与流感病毒的结合是饱和的、浓度依赖性的，并且需要Ca2+离子的存在。以MBP作为配体对病毒裂解物进行配体印迹分析表明，MBP与一种68 kDa的病毒蛋白结合。将该68 kDa的蛋白分离至均一，并证明其为病毒神经氨酸酶。纯化的68 kDa蛋白可抑制MBP和SP-A与流感病毒的结合。
