Calcium Ions Regulate Contraction of Smooth Muscle Cells by Binding

Question

Calcium ions regulate contraction of smooth muscle cells by binding to
A) troponin.
B) tropomyosin.
C) actin.
D) myosin.
E) calmodulin.

Accepted Answer

Calcium ions bind to calmodulin, which then activates myosin light chain kinase, leading to phosphorylation of myosin and initiation of muscle contraction in smooth muscle cells. Calcium does not directly bind to troponin, tropomyosin, or actin in smooth muscle cells.