Myosin light-chain kinase

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myosin, light polypeptide kinase
Identifiers
Symbol	MYLK
HUGO	7590
Entrez	4638
OMIM	600922
RefSeq	NM_053025
UniProt	Q15746
Other data
EC number	2.7.1.117
Locus	Chr. 3 qcen-q21

myosin light chain kinase 2, skeletal muscle
Identifiers
Symbol	MYLK2
HUGO	16243
Entrez	85366
OMIM	606566
RefSeq	NM_033118
UniProt	Q9H1R3
Other data
Locus	Chr. 20 q13.31

Myosin-light-chain kinase (MLCK) is a serine/threonine-specific protein kinase which phosphorylates myosin.

This protein is important in the mechanism of contraction in smooth muscle. Once there is an influx of calcium into the smooth muscle, either from the sarcoplasmic reticulum or more importantly from the extracellular space, contraction of smooth muscle fibres may begin. Firstly the calcium will bind to Calmodulin. This binding will activate the MLCK which will go on to phosphorylate the myosin light chain. This 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 like striated muscle, this mechanism is considered the main pathway by which smooth muscle regulates contraction.