Bao Z Z, Muschler J, Horwitz A F
Department of Cell and Structural Biology, University of Illinois, Urbana 61801.
J Biol Chem. 1992 Mar 5;267(7):4974-80.
A 190/220-kDa complex found in integrin preparations was purified, and monoclonal antibodies were raised against it. The immunoaffinity-purified complex appears to be a trimer of very similar or identical 70-kDa subunits. It is a novel extracellular matrix molecule as determined by its subunit composition, N-terminal amino acid sequence, and in vivo localization. It is distributed widely in basement membranes including those from muscle, nerve, and kidney. It is also present in connective tissue regions such as perineurium and perimysium. It has the unusual property that it is initially expressed very late in avian development near the time of hatching. This protein is found to copurified with integrin because it binds to the carbohydrate support in Sepharose. Hemagglutination assays with mono- and disaccharides show that it functions as a lectin with galactoside-binding specificity. This protein is also found to bind strongly and specifically to laminin at a site distinct from its lectin activity, but does not bind to fibronectin or type IV collagen. The protein appears to be conserved and is a common contaminant of many laminin preparations. We call this novel protein "LBL" for laminin-binding lectin.
在整合素制剂中发现的一种190/220 kDa复合物被纯化，并针对其制备了单克隆抗体。免疫亲和纯化的复合物似乎是由非常相似或相同的70 kDa亚基组成的三聚体。根据其亚基组成、N端氨基酸序列和体内定位，它是一种新型的细胞外基质分子。它广泛分布于基底膜，包括来自肌肉、神经和肾脏的基底膜。它也存在于结缔组织区域，如神经束膜和肌束膜。它具有一种不寻常的特性，即在鸟类发育后期孵化时才开始表达。发现这种蛋白质与整合素共纯化，因为它与琼脂糖中的碳水化合物载体结合。单糖和双糖的血凝试验表明，它作为一种具有半乳糖苷结合特异性的凝集素发挥作用。还发现这种蛋白质在与其凝集素活性不同的位点与层粘连蛋白强烈且特异性地结合，但不与纤连蛋白或IV型胶原结合。这种蛋白质似乎是保守的，并且是许多层粘连蛋白制剂中的常见污染物。我们将这种新型蛋白质称为“LBL”，即层粘连蛋白结合凝集素。
