Myosin light-chain kinase

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myosin, light polypeptide kinase
Symbol MYLK
Entrez 4638
HUGO 7590
OMIM 600922
RefSeq NM_053025
UniProt Q15746
Other data
EC number
Locus Chr. 3 qcen-q21
myosin light chain kinase 2, skeletal muscle
Symbol MYLK2
Entrez 85366
HUGO 16243
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. First the calcium will bind to Calmodulin. This binding will activate MLCK which will go on to phosphorylate the myosin light chain at serine residue 19. 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.

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