Structure-Function Relationship and Phosphorylation-Dependent Regulation of Intermediate Filament Proteins.

波形蛋白的氨基端头部结构域是几种蛋白激酶的靶位点，并且磷酸化在体内和体外诱导波形蛋白中间丝的分解。为了更好地了解磷酸化依赖性解体的分子机制，我们研究了涉及头部结构域的结构域相互作用和磷酸化对相互作用的影响，使用表面等离子体共振。我们观察到，头部结构域结合到杆结构域中的羧基末端螺旋2B，在生理离子强度。这种相互作用受到干扰的A-激酶磷酸化的头部结构域。螺旋2B的羧基末端20个氨基酸的缺失导致相互作用的丧失。此外，代表螺旋2B的羧基末端20个残基的肽与头部结构域有很大的亲和力，但与磷酸化的结构域没有亲和力。这些研究结果支持了这样的想法，头域和螺旋2B的最后20个残基之间的相互作用是必不可少的协会的波形蛋白四聚体到中间丝和磷酸化依赖的拆卸是损失的相互作用的结果。

The amino-terminal head domain of vimentin is the target site for several protein kinases and phosphorylation induces disassembly of the vimentin intermediate filaments in vivo and in vitro. To better understand molecular mechanisms involved in phosphorylation-dependent disassembly, we examined domain interactions involving the head domain and the effect of phosphorylation on the interaction, using surface plasmon resonance. We observed that the head domain binds to the carboxyl-terminal helix 2B in the rod domain, under physiological ionic strength. This interaction was interfered with by A-kinase phosphorylation of the head domain. Deletion of the carboxyl-terminal twenty amino acids of helix 2B resulted in loss of the interaction. Furthermore, peptide representing the carboxyl-terminal twenty residues of helix 2B had a substantial affinity with the head domain but not with the phosphorylated one. These findings support the idea that the interaction between the head domain and the last twenty residues of helix 2B is essential for association of vimentin tetramers into the intermediate filaments and that the phosphorylation-dependent disassembly is the result of loss of the interaction.