MYLK

• OMIM: 600 922
• UniProt: Q15746

The myosin light chain kinase ( MLKK ) and myosin light -chain kinase ( MLCK or MyLK ) is an enzyme in vertebrates. It can phosphorylate the regulatory light chain of Myosinmoleküls in smooth muscle cells. First the light chain inhibits the contraction of smooth muscle cells through phosphorylation, binding to actin are produced and the smooth muscle cell contraction.

Function

The main function of MLKK lies particularly in the regulation of vascular tone by smooth muscles in the bronchi and arterioles. The mechanism depends on the membrane potential of the smooth muscle cell: the more the membrane is depolarized, the more voltage-dependent Ca2 channels open and Ca2 flows into the cell. It forms a complex with the regulatory protein calmodulin ( Ca 2 / calmodulin complex), which activates the MLKK. This now phosphorylates the light chain of myosin, thereby disinhibited and the myosin head can be active as ATPase. (see also contractile mechanism )

The opponent is the MLK- phosphatase, which dephosphorylated light chain of myosin and thus inhibits. In striated muscle, there is a similar protein, the myosin light chain kinase - II with analogue mechanism of action.

Importance

In the treatment of asthma, to make use of this property in order to use by sympathomimetic on the G-protein coupled receptor ( β2 -adrenoceptors ) for bronchodilation.