The function of TPM4 (tropomyosin 4, ENSG00000167460) is as follows. Binds to actin filaments in muscle and non-muscle cells. 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. In non-muscle cells is implicated in stabilizing cytoskeleton actin filaments (By similarity). Binds calcium (PubMed:1836432). Plays a role in platelet biogenesis. {ECO:0000250|UniProtKB:P09495, ECO:0000269|PubMed:1836432, ECO:0000269|PubMed:28134622, ECO:0000269|PubMed:35170221}.