Mitogen-activated protein kinase
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 | edit source]
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 | edit source]
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 | edit source]
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 | edit source]
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 | edit source]
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 | edit source]
- Protein kinase
- Signal transduction
- Gene expression
- Apoptosis
- Cell proliferation
- ERK1/2
- JNK
- p38 MAPK
- ERK5
See Also[edit | edit source]
References[edit | edit source]
External Links[edit | edit source]
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Contributors: Prab R. Tumpati, MD