Erk

Erk 1.Erk signaling overview The extracellular-signal-regulated kinase (ERK) pathway is one of the major signaling cassettes of the mitogen activated protein kinase (MAPK) signaling pathway. The ERK cascade is activated by a variety of extracellular agents, including growth factors, hormones and also cellular stresses to induce cellular processes that include mainly proliferation and differentiation, but under some conditions also stress response and others.

The main MAPK/ERK kinase kinase (MEKK) components are the Raf family members Raf-1, A-Raf and B-Raf that phosphorylate two serine residues on the MAPK/ERK kinase (MEK) components MEK1/2. ERK1/2 are responsible for stimulating the downstream effectors, many of which are transcription factors. One of the major transcription factors is cyclic AMP response element-binding protein (CREB).

2.Erk signaling cascade The activation of the ERK1/2 cascade is mostly initiated at membrane receptors, such as receptor Tyr kinases (RTKs), G protein–coupled receptors (GPCRs), ion channels, and others. These receptors transmit the signal by recruiting adaptor proteins (e.g., Grb2) and exchange factors (e.g., SOS) that, in turn, induce the activation of Ras at the plasma membranes, or membranes of other organelles. The activated, GTP bound Ras then transmits the signal by activating the protein kinases Raf-1, B-Raf, and A-Raf (Rafs) within the MAP3K level of this cascade. This activation occurs by recruiting Rafs to the membranes, where they are then phosphorylated and activated. http://www.creative-diagnostics.com/Erk-Signaling-Pathway.htm