Frank Sabine, Schulthess Therese, Landwehr Ruth, Lustig Ariel, Mini Thierry, Jenö Paul, Engel Jürgen, Kammerer Richard A
Department of Biophysical Chemistry, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.
J Biol Chem. 2002 May 24;277(21):19071-9. doi: 10.1074/jbc.M202146200. Epub 2002 Mar 14.
Matrilins constitute a family of four oligomeric extracellular proteins that are involved in the development and homeostasis of cartilage and bone. To reveal their homo- and heterotypic oligomerization propensities, we analyzed the four human matrilin coiled-coil domains by biochemical and biophysical methods. These studies not only confirmed the homo- and heterotypic oligomerization states reported for the full-length proteins but revealed seven novel matrilin isoforms. Specific heterotrimeric interactions of variable chain stoichiometries were observed between matrilin-1 and matrilin-2, matrilin-1 and matrilin-4, and matrilin-2 and matrilin-4. In addition, matrilin-1 formed two different specific heterotetramers with matrilin-3. Interestingly, a distinct heterotrimer consisting of three different chains was formed between matrilin-1, matrilin-2, and matrilin-4. No interactions, however, were observed between matrilin-2 and matrilin-3 or between matrilin-3 and matrilin-4. Both homo- and heterotypic oligomers folded into parallel disulfide-linked structures, although coiled-coil formation was not dependent on disulfide bridge formation. Our results indicate that the heterotypic preferences seen for the matrilin coiled-coil domains are the result of the packing of the hydrophobic core rather than ionic interactions. Mass spectrometry revealed that the concentrations of the individual chains statistically determined the stoichiometry of the heteromers, suggesting that formation of the different matrillin chain combinations is controlled by expression levels.
基质蛋白构成了一个由四种寡聚细胞外蛋白组成的家族，它们参与软骨和骨骼的发育及稳态维持。为了揭示它们的同型和异型寡聚化倾向，我们通过生化和生物物理方法分析了四种人类基质蛋白的卷曲螺旋结构域。这些研究不仅证实了全长蛋白报道的同型和异型寡聚化状态，还揭示了七种新的基质蛋白异构体。在基质蛋白-1与基质蛋白-2、基质蛋白-1与基质蛋白-4以及基质蛋白-2与基质蛋白-4之间观察到了可变链化学计量的特异性异三聚体相互作用。此外，基质蛋白-1与基质蛋白-3形成了两种不同的特异性异四聚体。有趣的是，在基质蛋白-1、基质蛋白-2和基质蛋白-4之间形成了一种由三条不同链组成的独特异三聚体。然而，在基质蛋白-2与基质蛋白-3之间或基质蛋白-3与基质蛋白-4之间未观察到相互作用。同型和异型寡聚体均折叠成平行的二硫键连接结构，尽管卷曲螺旋的形成不依赖于二硫键的形成。我们的结果表明，基质蛋白卷曲螺旋结构域所见的异型偏好是疏水核心堆积的结果，而非离子相互作用。质谱分析表明，各条链的浓度在统计学上决定了异聚体的化学计量，这表明不同基质蛋白链组合的形成受表达水平控制。
