Myosin light chain kinase
| Myosin light chain kinase | ||
|---|---|---|
| Mass / length primary structure | 1914 amino acids | |
| Cofactor | Magnesium, calcium | |
| Isoforms | 8th | |
| Identifier | ||
| Gene name (s) | MYLK | |
| External IDs | ||
| Enzyme classification | ||
| EC, category | 2.7.11.18 , protein kinase | |
| Response type | Phosphorylation | |
| Substrate | ATP + [myosin light chain] | |
| Products | ADP + [myosin light chain] phosphate | |
| Occurrence | ||
| Parent taxon | Vertebrates | |
| Orthologue | ||
| human | House mouse | |
| Entrez | 4638 | 107589 |
| Ensemble | ENSG00000065534 | ENSMUSG00000022836 |
| UniProt | Q15746 | B1B1A8 |
| Refseq (mRNA) | NM_001321309 | NM_139300 |
| Refseq (protein) | NP_001308238 | NP_647461 |
| Gene locus | Chr 16: 123.61 - 123.88 Mb | Chr 16: 34.75 - 35 Mb |
| PubMed search | 4638 |
107589
|
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 the myosin molecule in smooth muscle cells . The light chain initially inhibits the contraction of smooth muscle cells, through phosphorylation a bond to actin can be established and the smooth muscle cell contracts.
function
The main function of MLKK lies in particular in the regulation of vascular tone by the smooth muscles of 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 Ca 2+ channels open and Ca 2+ flows into the cell. Here it forms a complex with the regulatory protein calmodulin (Ca 2+ / calmodulin complex), which activates the MLKK. This now phosphorylates the light chain of the myosin, whereby it is disinhibited and the myosin head can become active as an ATPase. (see also contractile mechanism )
The antagonist is MLK phosphatase, which dephosphorylates and thus inhibits the myosin light chain. A similar protein, myosin light chain kinase II with an analogous mechanism of action, is found in striated muscles.
meaning
This property is used in the treatment of asthma in order to use sympathomimetics via the G-protein-coupled receptors (β 2 -adrenoceptors) for bronchodilation.
literature
- Robert F. Schmidt, Florian Lang: Human Physiology . 30. ed.Berlin: Springer, 2007.
- Georg Löffler, Petro E. Petrides: Biochemistry and Pathobiochemistry . 8th ed. Berlin: Springer, 2006.
Individual evidence
- ↑ Homologues at inParanoid
- ^ R. Klinke, H. Pape, A. Kurtz & S. Silbernagl, Physiologie (6th edition), Georg Thieme Verlag. Stuttgart, 2010. ISBN 978-3-13-796006-5