TPM4 belongs to the tropomyosin family. Tropomyosins are present in virtually all eukaryotic cells (both muscle and nonmuscle), where they bind actin filaments and function to modulate actin-myosin interaction and stabilize actin filament structure. TPM4 binds to actin filaments in muscle and nonmuscle cells and plays a central role, in association with the troponin complex, in the calcium dependent regulation of vertebrate striated muscle contraction. Smooth muscle contraction is regulated by interaction with caldesmon. Recombinant human TPM4 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.