Smooth muscles depolarize as a result of a transmembrane current of Calcium ions. When an action potential depolarizes the muscle cell membrane, it also travels into the body of the cell via the t-tubules. Unlike skeletal muscle, smooth muscle is dependent in two sources of calcium in order to intiate contraction. These two sources are calcium sequestered in the S.R. of the smooth muscle cell.
According to the information given, the missing mRNA sequence strand is the 4th from the given option which is AUG AAA CGU CCU. As the complementary of A in RNA is U, G is C and for T is A.
