Creatine kinase, muscle also known as MCK is a
creatine kinase
Creatine kinase (CK), also known as creatine phosphokinase (CPK) or phosphocreatine kinase, is an enzyme () expressed by various tissues and cell types. CK catalyses the conversion of creatine and uses adenosine triphosphate (ATP) to create phosp ...
that in humans is encoded by the ''MCK''
gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
.
Structure
In the figure to the right, the crystal structure of the muscle-type M-CK monomer is shown. In vivo, two such monomers arrange symmetrically to form the active MM-CK enzyme.
Function
The protein encoded by this gene is a cytoplasmic enzyme involved in cellular energy
homeostasis
In biology, homeostasis (British English, British also homoeostasis) Help:IPA/English, (/hɒmɪə(ʊ)ˈsteɪsɪs/) is the state of steady internal, physics, physical, and chemistry, chemical conditions maintained by organism, living systems. Thi ...
. The encoded protein reversibly catalyzes the transfer of "energy-rich"
phosphate
In chemistry, a phosphate is an anion, salt, functional group or ester derived from a phosphoric acid. It most commonly means orthophosphate, a derivative of orthophosphoric acid .
The phosphate or orthophosphate ion is derived from phospho ...
between
ATP and creatine and between phospho-creatine and ADP. Its functional entity is a MM-CK homodimer in striated (sarcomeric) skeletal and cardiac muscle.
Clinical significance
In heart, in addition to the MM-CK homodimer, also the heterodimer MB-CK consisting of one muscle (M-CK) and one brain-type (
B-CK) subunit is expressed. The latter may be an important serum marker for
myocardial infarction
A myocardial infarction (MI), commonly known as a heart attack, occurs when blood flow decreases or stops to the coronary artery of the heart, causing damage to the heart muscle. The most common symptom is chest pain or discomfort which may ...
, if released from damaged myocardial cells into the blood where it can be detected by clinical chemistry.
References
Further reading
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External links
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