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The post-translational processing of ras p21 is critical for its stimulation of mitogen-activated protein kinase

T Itoh1, K Kaibuchi, T Masuda

  • 1Department of Biochemistry, Kobe University School of Medicine, Japan.

The Journal of Biological Chemistry
|February 15, 1993
PubMed

Insights

Post-translational processing of ras p21 is crucial for activating mitogen-activated protein (MAP) kinase signaling. A cell-free system demonstrated that processed ras p21, bound to GTP gamma S, effectively activates MAP kinase.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Biochemistry

Background:

  • Ras p21 proteins are key regulators of cellular signaling pathways.
  • Mitogen-activated protein (MAP) kinase/extracellular signal-regulated kinase (ERK) pathways are critical for cell growth and differentiation.
  • The precise mechanism by which ras p21 activates MAP kinase, particularly the role of post-translational modifications, requires further elucidation.

Purpose of the Study:

  • To investigate the role of ras p21 post-translational processing in MAP kinase activation.
  • To establish a cell-free system for studying ras p21-mediated MAP kinase activation.
  • To identify the downstream components necessary for ras p21-induced MAP kinase activation.

Main Methods:

  • Development of a cell-free system using Xenopus oocyte cytosol.
  • Utilizing guanosine 5'-(3-O-thio)triphosphate (GTP gamma S) and guanosine diphosphate (GDP) bound forms of processed and unprocessed Ki-ras 4B p21.
  • Assessing MAP kinase and recombinant ERK2 activation in response to different forms of ras p21.

Main Results:

  • The GTP gamma S-bound, post-translationally processed form of Ki-ras 4B p21 effectively activated MAP kinase in the Xenopus oocyte cytosol.
  • Unprocessed Ki-ras 4B p21 or GDP-bound forms showed significantly less MAP kinase activation.
  • Processed Ki-ras 4B p21 activated recombinant ERK2 in a cell-free system, highlighting the importance of processing.

Conclusions:

  • Post-translational processing of ras p21 is essential for its ability to activate MAP kinase.
  • The necessary components for ras p21-mediated MAP kinase activation are present in the cytosol.
  • This study provides a robust cell-free assay for dissecting ras p21 signaling.

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