Abstract. Phosphorylation of the regulatory light chain of myosin by the Ca2+/calmodulin-dependent myosin light chain kinase plays an important role in smooth muscle contraction, nonmuscle cell shape changes, platelet contraction, secretion, and other cellular processes.

What is phosphorylation of myosin light chain?

Abstract. Phosphorylation of the regulatory light chain of myosin by the Ca2+/calmodulin-dependent myosin light chain kinase plays an important role in smooth muscle contraction, nonmuscle cell shape changes, platelet contraction, secretion, and other cellular processes.

What does myosin phosphorylation do?

Myosin light chain phosphorylation enhances contraction of heart muscle via structural changes in both thick and thin filaments.

What happens when you phosphorylate myosin light chain kinase?

Myosin light chain kinase from smooth muscle has been shown to be phosphorylated by cyclic AMP-dependent protein kinase, which leads to a decrease in the affinity of the kinase for Ca2+ . calmodulin and, hence, a decrease in enzymatic activity.

How does myosin light chain work?

Myosin light chain kinase (MLCK) plays a central role in regulating the actin-myosin interaction of smooth muscle. MLCK phosphorylates the light chain of myosin in the presence of Ca2+ and calmodulin (CaM) thereby activating myosin so that it can interact with actin.

What are myosin regulatory light chains?

The myosin regulatory and essential light chains structurally support the neck region of myosin motor (cross-bridge) that powers cardiac and skeletal muscle contraction via chemomechanical transduction of ATP free energy used to produce the power stroke and drive striated muscle contraction (Geeves and Holmes 2005).

How is myosin light chain phosphatase activated?

When the muscle needs to contract, calcium ions flow into the cytosol from the sarcoplasmic reticulum, where they activate calmodulin, which in turn activates myosin light-chain kinase (MLC kinase). MLC kinase phosphorylates the myosin light chain (MLC20) at the Ser-19 residue.

Why does myosin need to be phosphorylated?

The phosphorylation of MLC will enable the myosin crossbridge to bind to the actin filament and allow contraction to begin (through the crossbridge cycle). Since smooth muscle does not contain a troponin complex, as striated muscle does, this mechanism is the main pathway for regulating smooth muscle contraction.

Is MLCK inhibited by phosphorylation?

Binding calmodulin to MLCK blocks phosphorylation of Ser-991 by PAK2. These results demonstrate that PAK2 can directly phosphorylate MLCK, inhibiting its activity and limiting the development of isometric tension.

When phosphorylated the myosin light chains of the smooth muscle will promote?

contraction
The phosphorylated form of CPI-17 inhibits myosin light chain phosphates (MLCP), thereby promoting the phosphorylated form of the myosin light chains, which promotes contraction.

What is regulatory light chain?

Myosin regulatory light chain 2, ventricular/cardiac muscle isoform (MLC-2) also known as the regulatory light chain of myosin (RLC) is a protein that in humans is encoded by the MYL2 gene.

Is myosin light chain in skeletal muscle?

IN muscle each myosin head contains a regulatory light chain (LC2) that is wrapped around the head/rod junction, and an alkali light chain that is distal to LC2 (ref. 1). The role of these light chains in vertebrate skeletal muscle myosin has remained obscure2,3.

What is latch bridge mechanism?

‘ A latch-bridge is defined as all those molecular force-generating states of dephosphorylated, slowly detaching cross-bridges. This model still provides robust quantitative predictions of the contractile properties of smooth muscle.