Leitinger Birgit, Steplewski Andrzej, Fertala Andrzej
Department of Medicine, The Sackler Institute for Muscular Skeletal Research, University College London, 5 University Street, London WC1E 6JJ, UK.
J Mol Biol. 2004 Dec 3;344(4):993-1003. doi: 10.1016/j.jmb.2004.09.089.
The human discoidin domain receptors (DDRs), DDR1 and DDR2, are expressed widely and, uniquely among receptor tyrosine kinases, activated by the extracellular matrix protein collagen. This activation is due to a direct interaction of collagen with the DDR discoidin domain. Here, we localised a specific DDR2 binding site on the triple-helical region of collagen II. Collagen II was found to be a much better ligand for DDR2 than for DDR1. As expected, DDR2 binding to collagen II was dependent on triple-helical collagen and was mediated by the DDR2 discoidin domain. Collagen II served as a potent stimulator of DDR2 autophosphorylation, the first step in transmembrane signalling. To map the DDR2 binding site(s) on collagen II, we used recombinant collagen II variants with specific deletions of one of the four repeating D periods. We found that the D2 period of collagen II was essential for DDR2 binding and receptor autophosphorylation, whereas the D3 and D4 periods were dispensable. The DDR2 binding site on collagen II was further defined by recombinant collagen II-like proteins consisting predominantly of tandem repeats of the D2 or D4 period. The D2 construct, but not the D4 construct, mediated DDR2 binding and receptor autophosphorylation, demonstrating that the D2 period of collagen II harbours a specific DDR2 recognition site. The discovery of a site-specific interaction of DDR2 with collagen II gives novel insight into the nature of the interaction of collagen II with matrix receptors.
人类盘状结构域受体（DDRs），即DDR1和DDR2，广泛表达，且在受体酪氨酸激酶中独一无二的是，它们可被细胞外基质蛋白胶原蛋白激活。这种激活是由于胶原蛋白与DDR盘状结构域的直接相互作用。在此，我们在胶原蛋白II的三螺旋区域定位了一个特定的DDR2结合位点。结果发现，胶原蛋白II作为DDR2的配体比作为DDR1的配体要好得多。正如预期的那样，DDR2与胶原蛋白II的结合依赖于三螺旋胶原蛋白，并由DDR2盘状结构域介导。胶原蛋白II是DDR2自身磷酸化的有效刺激物，这是跨膜信号传导的第一步。为了绘制DDR2在胶原蛋白II上的结合位点，我们使用了对四个重复D周期之一进行特定缺失的重组胶原蛋白II变体。我们发现，胶原蛋白II的D2周期对于DDR2结合和受体自身磷酸化至关重要，而D3和D4周期则是可有可无的。胶原蛋白II上的DDR2结合位点通过主要由D2或D4周期的串联重复组成的重组类胶原蛋白II蛋白进一步确定。D2构建体而非D4构建体介导了DDR2结合和受体自身磷酸化，这表明胶原蛋白II的D2周期包含一个特定的DDR2识别位点。DDR2与胶原蛋白II的位点特异性相互作用的发现为胶原蛋白II与基质受体相互作用的本质提供了新的见解。
