總結(jié) |
Troponin I (cTnI) is 1 of 3 subunits, along with troponin C (TnC) and troponin T (TnT) of troponin complex found in cardiac muscle. cTnI binds to actin in thin myofilaments to hold the troponin-tropomyosin complex in place, and when cTnI is phosphorylated by protein kinase C and protein kinase A at Ser23/24 it causes regulation of Ca2+- stimulated ATPase (Noland et al, 1995). Evidence suggests that phosphorylation of both serines 23 and 24 is required for the reduction in Ca2+-sensitivity and beneficial for relaxation of the heart (Kooij et al, 2010). Ser23/24 phosphorylation is important for enhanced relaxation in response to prolonged activation of protein kinase C by endothelin in intact myocytes, while Thr144 plays an important role in the acute acceleration of relaxation (Westfall et al, 2005).
|