Troponin I is the inhibitory subunit of troponin, the thin filament regulatory complex which confers calcium-sensitivity to muscle actomyosin ATPase activity. Strongly expressed in body wall muscle during embryogenesis, reduces during the larval stages to adult. In late-stage larvae and adults, expression is evident in the proximal gonad of both hermaphrodites and males. Worms exhibit abnormal locomotion. Belongs to the troponin I family.