Creatine Kinase (CK): A Comprehensive Review
Creatine Kinase (CK) is an enzyme that plays a critical role in energy metabolism. CK catalyzes the transfer of phosphate from ATP to creatine, forming phosphocreatine, which is a storage form of energy. CK is found in all types of cells, but is mainly located in skeletal muscle, cardiac muscle, and the brain. CK is involved in the regulation of energy balance and muscle contractility, as well as in the control of cell death and growth. This review provides an overview of CK and its role in health and disease.
Structure and Function
CK is a dimeric enzyme composed of two subunits, the M-subunit and the B-subunit. The M-subunit contains the catalytic site, while the B-subunit is responsible for the binding of substrate. CK is found in three forms: CK-MM, which is expressed in skeletal muscle; CK-MB, which is expressed in cardiac muscle; and CK-BB, which is expressed in the brain. Each form has a unique function and plays a distinct role in energy metabolism.
In skeletal muscle, CK-MM is involved in the production of energy during muscle contraction. During contraction, CK catalyzes the transfer of phosphate from ATP to creatine, forming phosphocreatine, which acts as a storage form of energy. This energy is then used to power contraction. In cardiac muscle, CK-MB is involved in the production of energy during muscle contraction and relaxation. It is also involved in the regulation of calcium homeostasis and the control of cell death and growth. In the brain, CK-BB is involved in the regulation of neuronal excitability and synaptic plasticity.
Clinical Significance
CK is an important biomarker of muscle damage, and elevated levels of CK can be indicative of a variety of muscle disorders. For example, elevated CK levels are seen in conditions such as myopathies, rhabdomyolysis, muscular dystrophy, and myocardial infarction. CK levels can also be used to monitor the effectiveness of treatments for these conditions. Additionally, CK levels can be used to detect the early stages of certain cancers, such as prostate and kidney cancer.
Conclusion
Creatine Kinase (CK) is a dimeric enzyme that plays a critical role in energy metabolism. CK is found in three forms: CK-MM, CK-MB, and CK-BB, each of which has a unique function. CK is an important biomarker of muscle damage, and elevated levels of CK can be indicative of a variety of muscle disorders. Additionally, CK levels can be used to detect the early stages of certain cancers.
References
Bastos, V. D., & Fernandes, P. A. (2020). Creatine kinase: Structure, function and clinical relevance. Clinica Chimica Acta, 508, 30-39.
Sotgia, F., & Lisanti, M. P. (2017). Creatine kinase: A versatile player in cancer. Trends in Cancer, 3(7), 459-469.
Perez-Schindler, J., & Guerrero-Romero, F. (2013). Creatine kinase isoenzymes: Clinical utility and interpretation of serum markers. Clinica Chimica Acta, 424, 1-7.