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The signal that starts the MAPK/ERK pathway is the binding of extracellular mitogen to a cell surface receptor. This allows a Ras protein (a Small GTPase) to swap a GDP molecule for a GTP molecule, flipping the "on/off switch" of the pathway. The Ras protein can then activate MAP3K (e.g., Raf), which activates MAP2K, which activates MAPK.
In the MAPK/ERK pathway, Ras activates c-Raf, followed by mitogen-activated protein kinase kinase (abbreviated as MKK, MEK, or MAP2K) and then MAPK1/2 (below). Ras is typically activated by growth hormones through receptor tyrosine kinases and GRB2/SOS, but may also receive other signals. ERKs are known to activate many transcription factors ...
The mating MAPK pathway consist of three tiers (Ste11-Ste7-Fus3), but the MAP2 and MAP3 kinases are shared with another pathway, the Kss1 or filamentous growth pathway. While Fus3 and Kss1 are closely related ERK-type kinases, yeast cells can still activate them separately, with the help of a scaffold protein Ste5 that is selectively recruited ...
Ras, from "Rat sarcoma virus", is a family of related proteins that are expressed in all animal cell lineages and organs. All Ras protein family members belong to a class of protein called small GTPase, and are involved in transmitting signals within cells (cellular signal transduction).
Mitogen-activated protein kinase kinase (also known as MAP2K, MEK, MAPKK) is a dual-specificity kinase enzyme which phosphorylates mitogen-activated protein kinase (MAPK). MAP2K is classified as EC 2.7.12.2. There are seven genes: MAP2K1 (a.k.a. MEK1) MAP2K2 (a.k.a. MEK2) MAP2K3 (a.k.a. MKK3) MAP2K4 (a.k.a. MKK4) MAP2K5 (a.k.a. MKK5) MAP2K6 (a ...
RAF kinases participate in the RAS-RAF-MEK-ERK signal transduction cascade, also referred to as the mitogen-activated protein kinase (MAPK) cascade. [11] Activation of RAF kinases requires interaction with RAS-GTPases. The three RAF kinase family members are: A-RAF; B-RAF; c-Raf
MAPK phosphatases (MKPs) are the largest class of phosphatases involved in down-regulating Mitogen-activated protein kinases (MAPK) signaling. [1] [2] MAPK signalling pathways regulate multiple features of development and homeostasis. [3] [4] This can involve gene regulation, cell proliferation, programmed cell death and stress responses. [5]
Over-expression of the MAPKKK upstream of the ERK 1/2 MAPK and an increase in epidermal growth factor receptor (EGFR) can lead to tumor formation, such as triple negative breast cancer. [14] A mutation in the JNK or p38 family of MAPK or their MAPKKK upstream precursors can result in Alzheimer's disease. This is also seen when there is too much ...