Abstract：
Tropomyosin (Tpm) is one of the most important partners of actin filament that largely determines its properties. In animal organisms, there are different isoforms of Tpm, which are believed to be involved in the regulation of various cellular functions. However, molecular mechanisms by which various Tpm cytoplasmic regulate of the functioning of actin filaments are still poorly understood. Here, we investigated the properties of Tpm2.1 and Tpm4.1 isoforms and compared them to each other and to more extensively studied Tpm isoforms. Tpm2.1 and Tpm4.1 were very similar in their affinity to F-actin, thermal stability, and resistance to limited proteolysis by trypsin, but differed markedly in the viscosity of their solutions and thermal stability of their complexes with F-actin. The main difference of Tpm2.1 and Tpm4.1 from other Tpm isoforms (e.g., Tpm1.6 and Tpm1.7) was their extremely low thermal stability as measured by the CD and DSC methods. We suggested the possible causes of this instability based on comparing the amino acid sequences of Tpm4.1 and Tpm2.1 with the sequences of Tpm1.6 and Tpm1.7 isoforms, respectively, that have similar exon structure.
摘要：
原肌球蛋白（Tpm）是肌动蛋白丝最重要的伙伴之一，在很大程度上决定了其性质。在动物有机体中，Tpm有不同的同工型，它们被认为参与各种细胞功能的调节。然而,各种Tpm细胞质调节肌动蛋白丝功能的分子机制仍然知之甚少。这里,我们研究了Tpm2.1和Tpm4.1亚型的性质，并将它们相互比较，并与更广泛研究的Tpm亚型进行比较。Tpm2.1和Tpm4.1对F-肌动蛋白的亲和力非常相似，热稳定性，以及对胰蛋白酶有限的蛋白水解的抗性，但是其溶液的粘度和与F-肌动蛋白的复合物的热稳定性显着不同。Tpm2.1和Tpm4.1与其他Tpm同工型的主要区别(例如，Tpm1.6和Tpm1.7）是通过CD和DSC方法测得的极低的热稳定性。我们基于比较Tpm4.1和Tpm2.1的氨基酸序列与Tpm1.6和Tpm1.7同工型的序列，提出了这种不稳定性的可能原因。分别,具有相似的外显子结构。
