PDF(Pubmed)
Abstract：
The actin cytoskeleton is one of the most important players in cell motility, adhesion, division, and functioning. The regulation of specific microfilament formation largely determines cellular functions. The main actin-binding protein in animal cells is tropomyosin (Tpm). The unique structural and functional diversity of microfilaments is achieved through the diversity of Tpm isoforms. In our work, we studied the properties of the cytoplasmic isoforms Tpm1.8 and Tpm1.9. The results showed that these isoforms are highly thermostable and differ in the stability of their central and C-terminal fragments. The properties of these isoforms were largely determined by the 6th exons. Thus, the strength of the end-to-end interactions, as well as the affinity of the Tpm molecule for F-actin, differed between the Tpm1.8 and Tpm1.9 isoforms. They were determined by whether an alternative internal exon, 6a or 6b, was included in the Tpm isoform structure. The strong interactions of the Tpm1.8 and Tpm1.9 isoforms with F-actin led to the formation of rigid actin filaments, the stiffness of which was measured using an optical trap. It is quite possible that the structural and functional features of the Tpm isoforms largely determine the appearance of these isoforms in the rigid actin structures of the cell cortex.
摘要：
肌动蛋白细胞骨架是细胞运动中最重要的参与者之一，附着力,司,和功能。特定微丝形成的调节在很大程度上决定了细胞功能。动物细胞中主要的肌动蛋白结合蛋白是原肌球蛋白(Tpm)。微丝的独特结构和功能多样性是通过Tpm同工型的多样性实现的。在我们的工作中,我们研究了细胞质同工型Tpm1.8和Tpm1.9的性质。结果表明，这些同工型具有高度的热稳定性，并且其中心和C末端片段的稳定性不同。这些同工型的性质主要由第6个外显子决定。因此，端到端互动的力量，以及Tpm分子对F-肌动蛋白的亲和力，Tpm1.8和Tpm1.9亚型之间存在差异。它们取决于是否有替代的内部外显子，6a或6b，包含在Tpm同工型结构中。Tpm1.8和Tpm1.9同工型与F-肌动蛋白的强相互作用导致刚性肌动蛋白丝的形成，其刚度是使用光学陷阱测量的。Tpm同工型的结构和功能特征很可能在很大程度上决定了这些同工型在细胞皮层的刚性肌动蛋白结构中的出现。
