Brain-type creatine kinase also known as CK-BB 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 ''CKB''
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 ...
.
Function
The protein encoded by this gene, CK-BB, consists of a homodimer of two identical brain-type CK-B subunits. BB-CK is a cytoplasmic enzyme involved in cellular energy homeostasis, with certain fractions of the enzyme being bound to cell membranes, ATPases, and a variety of ATP-requiring enzymes in the cell. There, CK-BB forms tightly coupled microcompartments for in situ regeneration of ATP that has been used up. 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 or between phospho-creatine (PCr) and ADP. Its functional entity is a homodimer (CK-BB) in brain and
smooth muscle
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
as well as in other tissues and cells such as neuronal cells, retina, kidney, bone, etc. In heart, a heterodimer (CK-MB) shahil consisting of one CK-B brain-type CK subunit and one CK-M muscle-type CK subunit is prominently expressed. The encoded CK-BB and CK-MB proteins are members of the
ATP:guanido phosphotransferase protein family.
Ectopic expression
Ectopic expression Ectopic is a word used with a prefix, ecto, meaning “out of place.” Ectopic expression is an abnormal gene expression in a cell type, tissue type, or developmental stage in which the gene is not usually expressed. The term ectopic expression is ...
(CKBE) of the B (brain) type of creatine kinase (CK-BB) in red cells and platelets is a rare, benign anomaly detected during a newborn screening program for
Duchenne muscular dystrophy
Duchenne muscular dystrophy (DMD) is a severe type of muscular dystrophy that primarily affects boys. Muscle weakness usually begins around the age of four, and worsens quickly. Muscle loss typically occurs first in the thighs and pelvis fol ...
.
References
External links
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