BIOL 2021 Lecture Notes - Lecture 13: Mitogen-Activated Protein Kinase Kinase, Protein Kinase, Scaffold Protein
13 May 2018
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• MAP kinase modules (856-857):
• Fig 15-49 MAP kinase module
o Both the tyrosine phosphorylations and the activation of Ras triggered by
activated RTKs are usually short-lived. Tyrosine-specific protein
phosphatases quickly reverse the phosphorylations, and Ras-GAPs
induce activated Ras to inactivate itself by hydrolyzing its bound GTP to
GDP. To stimulate cells to proliferate or differentiate, these short-lived
signaling events must be converted into longer-lasting ones that can
sustain the signal and relay it downstream to the nucleus to alter the
pattern of gene expression. One of the key mechanisms used for this
purpose is a system of proteins called the mitogen-activated protein
kinase module (MAP kinase module). The three components are all
protein kinases. The final kinase in the series is called simply MAP kinase
(MAPK). The next one upstream from this is MAP kinase kinase (MAPKK):
it phosphorylates and thereby activates MAP kinase. Next above that,
receiving an activating signal directly from Ras, is MAP kinase kinase
kinase (MAPKKK): it phosphorylates and thereby activates MAPKK.
o MAP kinase = mitogen activated protein kinase.
o Mitogen = stimulates proliferation = cell division.
o Conserved from yeast to humans.
o MAP kinase phosphorylates other proteins = proteins can be gene
regulatory proteins or other kinases. Protein that phosphorylates a MAP
kinase is a MAP kk. And MAP kkk activates MAP kk.
o MAP kinase kinase.
o MAP kinase kinase kinase.
o Ras activates MAP kkk.
o Causes long term results from changes in gene expression or other
protein activities.
• Scaffold proteins
• Fig 15-50 MAP kinase modules in yeast
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Document Summary
Map kinase modules (856-857), fig 15-49 map kinase module, both the tyrosine phosphorylations and the activation of ras triggered by activated rtks are usually short-lived. Tyrosine-specific protein phosphatases quickly reverse the phosphorylations, and ras-gaps induce activated ras to inactivate itself by hydrolyzing its bound gtp to. To stimulate cells to proliferate or differentiate, these short-lived signaling events must be converted into longer-lasting ones that can sustain the signal and relay it downstream to the nucleus to alter the pattern of gene expression. One of the key mechanisms used for this purpose is a system of proteins called the mitogen-activated protein kinase module (map kinase module). The final kinase in the series is called simply map kinase (mapk). The next one upstream from this is map kinase kinase (mapkk): it phosphorylates and thereby activates map kinase. Protein that phosphorylates a map kinase is a map kk.
