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在有Ｃａ２＋和钙调蛋白存在时，肌球蛋白轻链激酶催化肌球蛋白磷酸化，促使肌动蛋白激活的肌球蛋白（肌动球蛋白）Ｍｇ２＋－ＡＴＰ酶活性显著增加．然而，肌球蛋白磷酸化水平与Ｍｇ２＋－ＡＴＰ酶之间的关系是非线性的，原肌球蛋白可以进一步增加Ｍｇ２＋－ＡＴＰ酶的活性，但仍不改变它们之间的非线性关系．肌球蛋白轻链激酶的合成肽抑制剂抑制了肌球蛋白磷酸化和Ｍｇ２＋－ＡＴＰ酶活性，并导致平滑肌去膜肌纤维的等长收缩张力与速度的降低．结果提示肌球蛋白轻链激酶参与脊椎动物平滑肌收缩的调节过程，肌球蛋白轻链磷酸化作用会引起平滑肌收缩
In the presence of Ca2 + and calmodulin, myosin light chain kinase catalyzes myosin phosphorylation, leading to a significant increase in actin-activated myosin (actomyosin) Mg2 + -ATPase activity. However, the relationship between myosin phosphorylation and Mg2 + -ATPase is non-linear, and tropomyosin can further increase the activity of Mg2 + -ATPase but still does not change the non-linear relationship between them. Synthetic peptide inhibitors of myosin light chain kinase inhibit myosin phosphorylation and Mg2 + -ATPase activity and result in a reduction of the isometric systolic tone and speed of smooth muscle remover myofibers. The results suggest that myosin light chain kinase involved in the regulation of vertebrate smooth muscle contraction, myosin light chain phosphorylation can cause smooth muscle contraction