Creatina quinase: Diferenzas entre revisións
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Liña 22:
Nas células, os encimas CK "[[citosol|citosólicos]]" consta de dúas subunidades, que poden ser ''B'' (tipo cerebral, ''brain'' en inglés) ou ''M'' (tipo muscular). Porén, existen tres [[isoencima]]s: CK-MM, CK-BB e CK-MB. Os [[xene]]s destas subunidades están localizados en diferentes [[cromosoma]]s: ''B'' en [[cromosoma 14|14q32]] e ''M'' en [[cromosoma 19|19q13]]. Ademais destas tres isoformas de CK ''citosólicas'', hai dúas isoencimas CK [[mitocondria]]is, as formas ''ubicua'' e ''sarcomérica''. A entidade funcional destas dúas isoformas de CK mitocondrial é un octámero que catro dímeros.<ref name=pmid16236486>{{cite journal | vauthors = Schlattner U, Tokarska-Schlattner M, Wallimann T | title = Mitochondrial creatine kinase in human health and disease | journal = Biochimica et Biophysica Acta | volume = 1762 | issue = 2 | pages = 164–80 | date = February 2006 | pmid = 16236486 | doi = 10.1016/j.bbadis.2005.09.004 }}</ref>
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Mentres que a creatina quinase mitocondrial está directamente implicada na formación de fosfo-creatina a partir de ATP from mitocondrial, a CK citosólica rexenera o ATP a partir de ADP, usando a fosfocreatina. Isto acontece en sitios intracelulares onde se usa o ATP na célla, nos que a CK actúa como un rexenerador de ATP in situ.
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!
! proteína
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| [[CKB (
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| [[CKB (
| creatina quinase, expresión ectópica
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| [[CKM (
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| [[CKMT1A]], [[CKMT1B]]
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| [[CKMT2]]
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== Estruturas atómicas dos membros da familia da creatina quinase citosólicos e mitocondriais ==
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A number of genuine CK structures have been solved by high-resolution electron microscopy and protein X-ray crystallography by the two research groups led by Dr. Theo Wallimann at the Biol. Dept. ETH Zurich and by Dr. Wolfgang Kabsch at MPI in Heidelberg.
The first X-ray structure of a creatine kinase (CK) family member solved was that of sarcomeric muscle-type mitochondrial CK (s-mtCK (in 1996) (Fritz-Wolf et al. 1996 [http://publicationslist.org/data/theo.wallimann/ref-135/Fritz-Wolf-sMtCK%20structure.pdf]), later followed by the structure of ubiquitous u-mtCK in 2000. (Eder et al. 2000 [http://publicationslist.org/data/theo.wallimann/ref-101/Eder-X-ray.uMtCK.pdf]). Both mitochondrial CK isoforms are building highly symmetrical octameric structures with 4-fold symmetry. (Schnyder et al. 1990 [http://publicationslist.org/data/theo.wallimann/ref-184/Schnyder%201990%20Crystallization%20and%20preliminary%20X-ray%20of%20MtCk%20J%20Mol%20Biol.pdf]; Schnyder et al. 1991 [http://publicationslist.org/data/theo.wallimann/ref-180/SchnyderT_Gross-MtCK-crystal-EMs.pdf]). The atomic structure of cytosolic brain-type BB-CK was solved at 1.4 ! Angstoms in 1999. (Eder et al. 1999 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2144193/pdf/10595529.pdf]). Cytosolic BB-CK, as well as muscle-type MM-CK are both forming banana-shaped symmetric dimers, with one active site in each subunit. (Hornemann et al. 2000 [http://publicationslist.org/data/theo.wallimann/ref-96/Hornmann-CK-dimer.pdf]).
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