Troponin I, slow skeletal muscle, also known as TNNI1, belongs to the troponin I family. The troponin I subfamily contains three genes: TNNI-skeletal-fast-twitch, TNNI-skeletal-slow-twitch, and TNNI-cardiac. The TNNI-fast and TNNI-slow genes are expressed in fast-twitch and slow-twitch skeletal muscle fibers, respectively, while the TNNI-cardiac gene is expressed exclusively in cardiac muscle tissue. TNNI1 is the inhibitory subunit, blocking actin-myosin interactions and thereby mediating striated muscle relaxation.Synonyms: TNNI1