Center for Bioinformatics
Oxidoreductases | Transferases | Hydrolases | Lyases | Isomerases | Ligases

Basic Information

Enzyme Number

Official Name

myosin-light-chain kinase

Name from literature

myosin light chain kinase

Pathway from literature

initiation of myosin light chain phosphorylation

Pathway from KEGG

Cellular Processes; Cell Motility; Regulation of actin cytoskeleton; map04810

Environmental Information Processing; Signal Transduction; Calcium signaling pathway; map04020

Cellular Processes; Cell Communication; Focal adhesion; map04510


Human (9606)

Genome localization

3q21[4638 ], 16q11.2[91807 ], 20q13.31[85366 ],


Requires Ca2+ and calmodulin for activity. The 20-kDa light chain from smooth muscle myosin is phosphorylated more rapidly than any other acceptor, but light chains from other myosins and myosin itself can act as acceptors, but more slowly.

Rate-limiting Description

"It appears that the rate of conversion of myosin light chain kinase from an inactive to an active enzyme may be a significant rate limiting step for the initiation of myosin light chain phosphorylation." (2678154)

"Even more surprising was that the myosin heavy chain (MHC) isoform (SM-B) generally said to be associated with the higher shortening velocity disappeared from the cell, while the content of the key rate-limiting regulating enzyme, myosin light chain kinase (MLCK), increased 30-fold." (9612207)

"Comparison of the rate constants indicates that latch-bridge detachment is the rate-limiting step." (3337223)

Regulatory Information

Upstream transcription factor


Regulatory type



"Global, in vivo, and site-specific phosphorylation dynamics in signaling networks." (10748018)

key enzyme;

"Myosin light chain kinase (MLCK), a key enzyme in muscle contraction, has been shown by immunohistology to be present in neurons and glia." (8575746)


"EC MLCK activity appears to be highly dependent upon the phosphorylation status of this key contractile effector." (9806741)

transcriptional factor;"AP-1(3725),NFkappaB(4790)"

"Data show that either AP-1 or NFkappaB can up-regulate long MLCK transcription, but the mechanisms by which TNF up-regulates intestinal epithelial long MLCK transcription from exon 1A are differentiation-dependent." (16835238)

transcriptional factor;NFkappaB(4790)

"data indicate that the IL-1beta-induced increase in MLCK protein expression and Caco-2 TJ permeability was mediated by an increase in MLCK expression and activity and by an NF-kappaB-dependent increase in MLCK gene transcription" (18390750)





Gene ontology

Gene ontology

GO:0000287 (F) magnesium ion binding [Q32MK0, Q15746 ];
GO:0004683 (F) calmodulin-dependent protein kinase activity [Q9H1R3 ];
GO:0055008 (P) cardiac muscle morphogenesis [Q9H1R3 ];
GO:0060048 (P) cardiac muscle contraction [Q9H1R3 ];
GO:0006468 (P) protein amino acid phosphorylation [Q32MK0, Q15746, Q9H1R3 ];
GO:0005524 (F) ATP binding [Q32MK0, Q15746, Q9H1R3 ];
GO:0005509 (F) calcium ion binding [Q15746 ];
GO:0004687 (F) myosin light chain kinase activity [Q32MK0, Q15746, Q9H1R3 ];
GO:0005516 (F) calmodulin binding [Q15746, Q9H1R3 ];
GO:0032027 (F) myosin light chain binding [Q9H1R3 ];
GO:0032971 (P) regulation of muscle filament sliding [Q9H1R3 ];
GO:0030017 (C) sarcomere [Q9H1R3 ];

Tissue expression

Tissue From HPRD

Hippocampus [02952 ];
Jejunum [02952 ];
Fetus [02952 ];
Dermal microvascular endothelial cell [02952 ];
Liver [05953, 02952 ];
Muscle [05953 ];
Brain [05953, 02952 ];
Villus [02952 ];
Kidney [05953, 02952 ];
Smooth muscle [02952 ];
Heart [05953, 02952 ];
Frontal cortex [02952 ];
Lung [05953, 02952 ];
Pancreas [05953, 02952 ];
Entorhinal cortex [02952 ];
Placenta [05953, 02952 ];
Umbilical vein endothelial cell [02952 ];
Vascular endothelium [02952 ];

Tissue specificity

Heart and skeletal muscles. Increased expression in the apical tissue compared to the interventricular septal tissue [Q9H1R3 ];

Smooth muscle and non-muscle isozymes are expressed in a wide variety of adult and fetal tissues and in cultured endothelium with qualitative expression appearing to be neither tissue- nor development-specific. Non-muscle isoform 2 is the dominant splice variant expressed in various tissues. Telokin has been found in a wide variety of adult and fetal tissues [Q15746 ];

Subcellular localization


myofibril [Q9H1R3 ];

cytoplasm [Q9H1R3 ];

Disease relevance


Defects in MYLK2 are a cause of cardiomyopathy familial hypertrophic (CMH) [MIM:192600];
also designated FHC or HCM. Familial hypertrophic cardiomyopathy is a hereditary heart disorder characterized by ventricular hypertrophy, which is usually asymmetric and often involves the interventricular septum. The symptoms include dyspnea, syncope, collapse, palpitations, and chest pain. They can be readily provoked by exercise. The disorder has inter- and intrafamilial variability ranging from benign to malignant forms with high risk of cardiac failure and sudden cardiac death [Q9H1R3 ];



Q15746; Q32MK0; Q9H1R3

Entrez Gene

4638; 85366; 91807


02952; 05953; 11281

  Copyright 2009, Center for Bioinformatics 
  Last Modified: 2009-03-24  
  Design by Zhao Min