Myosin II
Myosin-II is a dimeric motor protein in eukaryotic cells . It occurs in the sarcomere of the skeletal muscles and is essential for muscle contraction .
construction
Myosin-II consists of 6 subunits, 2 heavy and 4 light chains. It has a molecular mass of around 490 kDa. Structurally, one can distinguish a head, neck and tail part. The head part has an ATP binding pocket with an ATPase activity , i. H. the nucleotide triphosphate , adenosine triphosphate , can be split into adenosine diphosphate and phosphate .
function
As a motor protein, Myosin-II is necessary for muscle contraction in the striated muscles. With the head part, Myosin-II can anchor itself to binding sites in the actin filament . These binding sites are covered by tropomyosin , a filamentous protein. Only when calcium ions bind to troponin C , then tropomyosin is pushed aside by conformational change and myosin-II can bind to the actin filament (see contractile mechanism ).
literature
- Aguilar, HN; Mitchell, S .; Knoll, AH; Yuan, X. (2010). "Physiological pathways and molecular mechanisms regulating uterine contractility". Human Reproduction Update 16 (6): 725-744. doi : 10.1093 / humupd / dmq016 . PMID 20551073 .
Individual evidence
- ↑ von der Ecken, J .; Müller, M .; Lehman, W .; Manstein, DJ; Penczek, PA; Raunser, S .: Structure of the F-actin-tropomyosin complex . In: Nature . 519, No. 7541, May 2015, pp. 114-7. doi : 10.1038 / nature14033 . PMID 25470062 .
- ↑ von der Ecken, J .; Heissler, SM; Pathan-Chhatbar, S .; Manstein, DJ; Raunser, S .: Cryo-EM structure of a human cytoplasmic actomyosin complex at near-atomic resolution. In: Nature. 534 (7609), 2016, pp. 724-728 (2016) PMID 27324845