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The posttranslational processing of ras p21 is critical for its stimulation of yeast adenylate cyclase

H Horiuchi1, K Kaibuchi, M Kawamura

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

Molecular and Cellular Biology
|October 1, 1992
PubMed

Insights

Posttranslational processing of mammalian ras proteins (p21s) is crucial for activating yeast adenylate cyclase. Fully processed ras p21s are significantly more effective activators than unprocessed forms.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Mammalian ras genes can functionally replace the yeast RAS gene, activating adenylate cyclase.
  • Ras p21 proteins undergo extensive posttranslational modifications, including prenylation, proteolysis, methylation, and palmitoylation, primarily at their C-terminal regions.
  • Previous studies indicated that posttranslational processing is vital for Ki-ras p21's interaction with smg GDS, a GDP/GTP exchange protein.

Purpose of the Study:

  • To investigate the critical role of posttranslational processing of Ki- and Ha-ras p21 proteins in stimulating yeast adenylate cyclase activity.
  • To determine if processing affects the interaction of ras p21s with their target proteins in a cell-free system.

Main Methods:

  • Utilized a cell-free system to assay yeast adenylate cyclase activity.
  • Compared the activity of posttranslationally processed and unprocessed forms of Ki-ras and Ha-ras p21 proteins.
  • Analyzed the interaction of ras p21s with relevant proteins.

Main Results:

  • Posttranslationally fully processed Ki-ras and Ha-ras p21 proteins demonstrated significantly higher activation of yeast adenylate cyclase compared to their unprocessed counterparts.
  • The efficiency of adenylate cyclase activation directly correlated with the extent of ras p21 posttranslational processing.

Conclusions:

  • Posttranslational processing of ras p21 proteins is essential for their effective stimulation of yeast adenylate cyclase.
  • These findings suggest that processing is critical for ras p21s' interaction with both smg GDS and their direct target protein(s) involved in adenylate cyclase regulation.

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