The compact conformation of fibronectin is determined by intramolecular ionic interactions
The compact conformation of fibronectin is determined by intramolecular ionic interactions
复制标题
DOI：
10.1074/jbc.274.22.15473
复制
发表时间：
1999-05-28
影响因子：
4.8
通讯作者：
Erickson, HP
中科院分区：
文献类型：
--
作者：
Johnson, KJ;Sage, H;Erickson, HP
纤维连接蛋白以紧密或伸展的构象存在，取决于环境的pH值和盐浓度。利用在细菌和杆状病毒中表达的重组片段，我们确定了负责产生纤维连接蛋白致密构象的结构域。我们的速度和平衡沉降数据表明，FN2-14（一种含有FN-III结构域2至14的蛋白质）在低盐条件下形成二聚体。小片段实验表明，二聚体中一个亚基的FN12-14与另一个亚基的FN2-3结合产生了致密构象，这种结合在较高的盐浓度下减弱，表明存在静电相互作用。此外，片段FN7-14+A包含在FN11和12之间选择性拼接的A结构域，形成二聚体，而不含A的FN7-14则不形成二聚体。片段FN12-14+A也形成二聚体，但孤立的A结构域不形成二聚体。这些数据表明结构域A与FN12-14存在关联，并且A的存在可能通过与FN2-3竞争与FN12-14结合而有利于开放构象。
Fibronectin exists in a compact or extended conformation, depending upon environmental pH and salt concentration. Using recombinant fragments expressed in bacteria and baculovirus, we determined the domains responsible for producing fibronectin's compact conformation. Our velocity and equilibrium sedimentation data show that FN2-14 (a protein containing FN-III domains 2 through 14) forms dimers in low salt. Experiments with smaller fragments indicates that the compact conformation is produced by binding of FN12-14 of one subunit to FN2-3 of the other subunit in the dimer, The binding is weakened at higher salt concentrations, implying an electrostatic interaction. Furthermore, segment FN7-14+A, which contains the alternatively spliced A domain between FN11 and 12, forms dimers, whereas FN7-14 without A does not. Segment FN12-14+A also forms dimers, but the isolated A domain does not. These data imply an association of domain A with FN12-14, and the presence of A may favor an open conformation by competing with FN2-3 for binding to FN12-14.