IDENTIFICATION AND CHARACTERIZATION OF TAGLIN, A MANNOSE 6-PHOSPHATE BINDING, TRYPSIN-ACTIVATED LECTIN FROM GIARDIA-LAMBLIA
IDENTIFICATION AND CHARACTERIZATION OF TAGLIN, A MANNOSE 6-PHOSPHATE BINDING, TRYPSIN-ACTIVATED LECTIN FROM GIARDIA-LAMBLIA
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DOI：
10.1021/bi00400a027
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发表时间：
1987-12-29
期刊：
影响因子：
2.9
通讯作者：
PEREIRA, MEA
中科院分区：
文献类型：
--
作者：
WARD, HD;LEV, BI;PEREIRA, MEA
我们之前已经报道过在蓝氏贾第鞭毛虫中存在与细胞表面相关的凝集素活性，这是一种人类原虫寄生虫，是全球腹泻疾病的重要原因[Lev，B.，Ward，H.，Keusch，G.T.和Pereira，M.E.A.(1986)Science(Washington，DC.)232，71-73]。这种凝集素在体外被体内感染部位分泌的一种宿主蛋白酶--胰蛋白酶特异性激活。激活的凝集素在体内凝集寄生虫附着的细胞，并特异性地结合到这些细胞的孤立刷状缘膜上。这些发现表明，这种凝集素在宿主-寄生虫的相互作用中可能是重要的。我们现在报告这种凝集素的鉴定，我们将其命名为Taglin(表示胰酶激活的贾第虫凝集素)，并描述了它的一些性质。抑制Taglin血凝活性的单抗可在贾第虫裂解物的Western印迹中识别28,000/30,000 kdalton的蛋白质。这一发现被用红细胞与硝酸纤维蛋白电印迹结合蛋白的技术直接显示凝集素活性所证实，这表明红细胞与心脏蛋白的特异性结合在与单抗识别的分子量相同的范围内。这项研究还阐明了Taglin与末端磷酸甘露醇残基的结合。细胞表面的磷酸盐参与了Taglin与红细胞的结合，表现为红细胞经碱性磷酸酶处理后凝集素活性被取消。Taglin还需要二价阳离子，即Ca~(2+)或Mn~(2+)来进行血凝活性，并在6-7的狭窄pH范围内发挥活性。
We have previously reported the presence of a cell surface associated lectin activity in Giardia lamblia, a human protozoan parasite that is a significant cause of diarrheal disease worldwide [Lev, B., Ward, H., Keusch, G. T., and Pereira, M. E. A. (1986) Science (Washington, D.C.) 232, 71-73]. This lectin is specifically activated in vitro by a host protease, trypsin, which is secreted in vivo at the site of infection. The activated lectin agglutinates cells to which the parasite adheres in vivo and binds specifically to isolated brush border membranes of these cells. These findings suggest that this lectin may be of importance in the host-parasite interaction. We now report the identification of this lectin, which we have named taglin (to denote trypsin-activated Giardia lectin), and describe some of its properties. A monoclonal antibody that inhibits the hemagglutinating activity of taglin recognizes a protein of 28,000/30,000 kdaltons in Western blots of Giardia lysates. This finding was confirmed by direct demonstration of lectin activity with the technique of erythrocyte binding to proteins electroblotted to nitrocellulose, which revealed specific red cell binding to giardial protein bands in the same molecular weight range as those recognized by the monoclonal antibody. This study also elucidates the binding of taglin to terminal phosphomannosyl residues. The involvement of cell surface phosphate in binding of taglin to erythrocytes is shown by the abolition of lectin activity by alkaline phosphatase treatment of the erythrocytes. Taglin also requires divalent cations, Ca2+ or Mn2+, for hemagglutinating activity and is active within a narrow pH range of 6-7.