PKA phosphorylates Myosin Binding Protein-C (MyBP-C) and troponin I (TnI) in the cardiac myofibril. TnI may be the inhibitory ingredient from the trimeric troponin molecule which makes up the Ca2+-swap in the contractile equipment. TnI binds to TnC when Ca2+ is bound to TnC, whilst in the absence of Ca2+, https://boyst727wwv1.wikipublicity.com/user