Mitogen-activated protein kinase

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ERK2-phosphorylated

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Raf-activation-cycle-sketch

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MAPK-pathway-mammalian

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MAPK-pathway-yeast

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MAPK-evolutionary-tree

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D-motif-overview

Mitogen-activated protein kinase (MAPK) is a type of protein kinase that is specific to the amino acids serine, threonine, and tyrosine. MAPKs are involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock, and proinflammatory cytokines. They regulate various cellular activities, including gene expression, mitosis, differentiation, proliferation, and cell survival/apoptosis.

Function[edit]

MAPKs are integral to the signal transduction pathways that convey extracellular signals to the intracellular machinery. They are activated through a cascade of phosphorylation events, typically involving a three-tiered kinase module: a MAPK kinase kinase (MAPKKK), a MAPK kinase (MAPKK), and the MAPK itself. This cascade ensures the amplification and specificity of the signal.

Types of MAPKs[edit]

There are several types of MAPKs, each with distinct functions and activation mechanisms:

ERK1/2 (Extracellular signal-regulated kinases)
JNK (c-Jun N-terminal kinases)
p38 MAPK
ERK5 (also known as BMK1)

Activation Mechanism[edit]

The activation of MAPKs involves a series of phosphorylation events. Typically, a MAPKKK phosphorylates and activates a MAPKK, which in turn phosphorylates and activates the MAPK. This phosphorylation usually occurs on specific threonine and tyrosine residues within the activation loop of the MAPK.

Biological Roles[edit]

MAPKs play crucial roles in various cellular processes:

Cell Growth and Proliferation: ERK1/2 pathways are often associated with cell growth and proliferation.
Stress Response: JNK and p38 MAPKs are typically activated in response to stress stimuli and are involved in the regulation of apoptosis.
Differentiation: MAPKs are involved in the differentiation of various cell types.
Inflammation: p38 MAPK is particularly important in the inflammatory response.

Clinical Significance[edit]

Dysregulation of MAPK pathways is implicated in various diseases, including cancer, diabetes, and neurodegenerative diseases. Targeting MAPK pathways is a therapeutic strategy in the treatment of these conditions.

Related Pages[edit]

References[edit]

External Links[edit]

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