The troponin complex controls muscle contraction by moving tropomyosin, a protein that blocks myosin from binding to actin when the muscle is relaxed. It consists of three subunits: Troponin C (TnC), Troponin I (TnI), and Troponin T (TnT). Troponin C (TnC) detects calcium. When a muscle fiber receives an electrical signal, calcium ions (Ca²⁺) are released from the sarcoplasmic reticulum into the sarcoplasm. These ions bind to TnC, causing it to change shape. TnC has two binding sites that always

Understanding Tropomyosin's Role in Muscle Contraction