Charonis A S, Tsilibary E C, Saku T, Furthmayr H
J Cell Biol. 1986 Nov;103(5):1689-97. doi: 10.1083/jcb.103.5.1689.
Laminin is a major glycoprotein of the basement membrane. Although its precise localization and orientation within this structure is unknown, it is presumably anchored to other macromolecules such as type IV collagen or proteoheparan sulfate. In vitro, laminin has the ability to self-assemble and to bind to type IV collagen molecules at distinct sites. To identify more precisely the domains of the complex, cross-shaped laminin molecule that are involved in these interactions, images of laminin-laminin dimers and laminin-type IV collagen complexes obtained by the rotary shadowing method were analyzed. We observed that the complex domain at the end of the long arm of laminin is predominantly involved in these interactions. By using Fab fragments of antibodies specific for a peptide fragment derived from this complex domain, it is shown that laminin self-assembly is inhibited in their presence, as measured by turbidity and by electron microscopy. In addition, these antibodies inhibit the specific interaction of laminin with type IV collagen. These data suggest that the complex domain at the end of the long arm of laminin contains binding sites of potential importance for the assembly of basement membranes.
层粘连蛋白是基底膜的一种主要糖蛋白。尽管其在该结构中的精确定位和取向尚不清楚，但推测它锚定在其他大分子上，如IV型胶原或硫酸乙酰肝素蛋白聚糖。在体外，层粘连蛋白具有自我组装的能力，并能在不同位点与IV型胶原分子结合。为了更精确地鉴定参与这些相互作用的十字形层粘连蛋白分子复合物的结构域，对通过旋转阴影法获得的层粘连蛋白-层粘连蛋白二聚体和层粘连蛋白-IV型胶原复合物的图像进行了分析。我们观察到，层粘连蛋白长臂末端的复合物结构域主要参与这些相互作用。通过使用针对源自该复合物结构域的肽片段的特异性抗体的Fab片段，结果表明，在它们存在的情况下，层粘连蛋白的自我组装受到抑制，这通过浊度和电子显微镜测量得以证实。此外，这些抗体抑制层粘连蛋白与IV型胶原的特异性相互作用。这些数据表明，层粘连蛋白长臂末端的复合物结构域包含对基底膜组装具有潜在重要性的结合位点。
