Synonyms: MB, M-B, MB-CK
Creatine kinase is found in vertebrate tissues with high and fluctuating energy demand including muscle (skeletal and cardiac), brain, retina and spermatozoa. It appears to be absent in liver [Wyss00].
In mammals and birds, four types of subunits are expressed in a species-specific, tissue-specific, and developmental stage-specific manner. Cytosolic muscle (M) and brain (B) subunits form creatine kinase MM isoform, creatine kinase BB isoform and creatine kinase MB isoform isozymes. Two mitochondrial isoforms are found, ubiquitous mitochondrial creatine kinase expressed in brain, kidney and other tissues and sarcomeric mitochondrial creatine kinase expressed in skeletal and heart muscle cells [Payne]. Both of these forms form interconvertible homodimers and homooctamers. Evidence suggests that the homooctameric form is the predominant form in vivo and is important for its function in [Schlattner00].
Creatine kinase is a member of the highly conserved phosphagen (guanidino) kinases that also include arginine, glycoyamine, hypotaurocyamine, lombricine, opheline and thalassemine kinases. Creatine kinase is the only phosphagen kinase used by lower chordates and vertebrates [Bertin07, Tanaka07].
A variety of creatine kinase assays exist, due to their use as clinical indicators of myocardial and skeletal muscle disorders and as a marker for myocardial infarction [McLeish05].
Enzymatic reaction of: creatine kinase
EC Number: 220.127.116.11creatine + ATP ⇄ creatine-phosphate + ADP + H+
The direction shown, i.e. which substrates are on the left and right sides, is in accordance with the direction of enzyme catalysis.
This reaction is reversible. [Wyss00]
In Pathways: creatine-phosphate biosynthesis
Normal, enzymatically active heterodimeric MB isozyme was prepared from purified muscle and brain component polypeptide chains and analyzed using steady state kinetics [Jacobs80].
Partially purified MM, BB and MB isoforms were anlayzed kinetically. The MB isoform showed intermediate values between the MM and BB isoforms in velocity versus substrate response using a luciferase-based assay system [Witteveen74].
Synonyms: Creatine kinase M chain, M-CK
|Gene:||CKM||Accession Number: HS02640 (HumanCyc)|
Synonyms: B-CK, Creatine kinase B chain
|Gene:||CKB||Accession Number: HS09344 (HumanCyc)|
Unification Links: Entrez:AAA52024, Entrez:AAA76850, Entrez:AAA76851, Entrez:AAA76852, Entrez:AAC31758, Entrez:AAH01190, Entrez:AAH04914, Entrez:AAH08323, Entrez:AAH10002, Entrez:AAH19259, Entrez:AAH19281, Entrez:CAA33389, MOPED:P12277, UniProt:P12277
Jacobs80: Jacobs HK, Kuby SA (1980). "Studies on muscular dystrophy. A comparison of the steady kinetics of the normal human ATP-creatine transphosphorylase isoenzymes (creatine kinases) with those from tissues of Duchenne muscular dystrophy." J Biol Chem 255(18);8477-82. PMID: 7410371
Schlattner00: Schlattner U, Eder M, Dolder M, Khuchua ZA, Strauss AW, Wallimann T (2000). "Divergent enzyme kinetics and structural properties of the two human mitochondrial creatine kinase isoenzymes." Biol Chem 381(11);1063-70. PMID: 11154064
Tanaka07: Tanaka K, Uda K, Shimada M, Takahashi K, Gamou S, Ellington WR, Suzuki T (2007). "Evolution of the cytoplasmic and mitochondrial phosphagen kinases unique to annelid groups." J Mol Evol 65(5);616-25. PMID: 17932618
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