Required for proper contractility of visceral smooth muscle cells (PubMed:28292896). Mediates nucleation of actin filaments. Colocalizes with actin filaments in sarcomeres. Detected in lung vascular smooth muscle (at protein level) (PubMed:27144530). Detected in thyroid and extraocular smooth muscle, but not skeletal muscle (PubMed:2026759). Detected in heart, aorta, skeletal muscle, colon, urinary bladder, uterus, stomach, and small intestine (PubMed:11318603). The disease is caused by variants affecting the gene represented in this entry. Belongs to the tropomodulin family.