Creatina quinase: Diferenzas entre revisións

 

== Estruturas atómicas dos membros da familia da creatina quinase citosólicos e mitocondriais ==

 

== Funcións ==

The [[mitochondrial]] creatine kinase (CK_m) is present in the mitochondrial intermembrane space, where it regenerates [[phosphocreatine]] (PCr) from mitochondrially generated ATP and [[creatine]] (Cr) imported from the [[cytosol]]. Apart from the two mitochondrial CK isoenzyme forms, that is, ubiquitous mtCK (present in non-muscle tissues) and sarcomeric mtCK (present in sarcomeric muscle), there are three cytosolic CK isoforms present in the cytosol, depending on the tissue. Whereas MM-CK is expressed in sarcomeric muscle, that is, skeletal and cardiac muscle, MB-CK is expressed in cardiac muscle, and BB-CK is expressed in smooth muscle and in most non-muscle tissues. Mitochondrial mtCK and cytosolic CK are connected in a so-called PCr/Cr-shuttle or circuit. PCr generated by mtCK in mitochondria is shuttled to cytosolic CK that is coupled to ATP-dependent processes, e.g. ATPases, such as acto-myosin ATPase and calcium ATPase involved in muscle contraction, and sodium/potassium ATPase involved in sodium retention in the kidney. The bound cytosolic CK accepts the PCr shuttled through the cell and uses ADP to regenerate ATP, which can then be used as energy source by the ATPases (CK is associated intimately with the ATPases, forming a functionally coupled microcompartment). PCr is not only an energy buffer but also a cellular transport form of energy between subcellular sites of energy (ATP) production (mitochondria and glycolysis) and those of energy utilization (ATPases).<ref name=pmid1731757/>

Thus, CK enhances skeletal, cardiac, and smooth muscle contractility, and is involved in the generation of [[blood pressure]].<ref name="pmid17075013">{{cite journal | vauthors = Brewster LM, Mairuhu G, Bindraban NR, Koopmans RP, Clark JF, van Montfrans GA | title = Creatine kinase activity is associated with blood pressure | journal = Circulation | volume = 114 | issue = 19 | pages = 2034–9 | date = November 2006 | pmid = 17075013 | doi = 10.1161/CIRCULATIONAHA.105.584490 | url = http://circ.ahajournals.org/content/114/19/2034.full.pdf | format = pdf }}</ref>