MAP/microtubule affinity-regulating kinase 4 is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that in humans is encoded by the ''MARK4''

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. MARK4 belongs to the family of

serine/threonine kinase A serine/threonine protein kinase () is a kinase enzyme, in particular a protein kinase, that phosphorylates the OH group of the amino-acid residues serine or threonine, which have similar side chains. At least 350 of the 500+ human prote ...

s that phosphorylate

microtubule-associated protein In cell biology, microtubule-associated proteins (MAPs) are proteins that interact with the microtubules of the cellular cytoskeleton. MAPs are integral to the stability of the cell and its internal structures and the transport of components withi ...

s (MAP) causing their detachment from

microtubule Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells. Microtubules can be as long as 50 micrometres, as wide as 23 to 27 nanometer, nm and have an inner diameter bet ...

s. Detachment thereby increases microtubule dynamics and facilitates a number of cell activities including

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

cell cycle The cell cycle, or cell-division cycle, is the sequential series of events that take place in a cell (biology), cell that causes it to divide into two daughter cells. These events include the growth of the cell, duplication of its DNA (DNA re ...

control,

cell polarity Cell polarity refers to spatial differences in shape, structure, and function within a cell. Almost all cell types exhibit some form of polarity, which enables them to carry out specialized functions. Classical examples of polarized cells are de ...

determination, and cell shape alterations. There are four members of the MARK protein family, MARK1-4, which are highly conserved. MARK4 kinase has been shown to be involved in microtubule organization in neuronal cells. Levels of MARK4 are elevated in

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

and may contribute to the pathological phosphorylation of

tau protein The tau proteins (abbreviated from tubulin associated unit) form a group of six highly soluble protein isoforms produced by alternative splicing from the gene ''MAPT'' (microtubule-associated protein tau). They have roles primarily in maintainin ...

in this disease.

Interactions

MARK4 has been shown to interact with

USP9X Probable ubiquitin carboxyl-terminal hydrolase FAF-X is an enzyme that in humans is encoded by the ''USP9X'' gene. Function This gene is a member of the peptidase C19 family and encodes a protein that is similar to ubiquitin-specific protease ...

and Ubiquitin C.

Interactions

References

Further reading