Q. What is the function of the enzyme activated by the calciumcalmodulin complex?
(A) Binding to troponin
(B) Dephosphorylation of actin
(C) Dephosphorylation of myosin
(D) Phosphorylation of actin
(E) Phosphorylation of myosin
Ans: E.
The calcium calmodulin complex activates myosin light chain kinase, which phosphorylates myosin and allows it to bind to actin, leading to contraction and shortening of the muscle fiber.
·
In
smooth muscle, unlike skeletal muscle, there is no troponin. Instead, calcium
is the regulator of myosin on the thick filament.
·
Actin
is not phosphorylated or dephosphorylated in the contraction and relaxation
cycle of smooth muscle.
·
The
calcium-calmodulin complex activates myosin light chain Kinase which phosphorylates myosin.
·
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