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The effector loop and prenylation site of R-Ras are involved in the regulation of integrin function

B Oertli1, J Han, B M Marte

  • 1Department of Vascular Biology, The Scripps Research Institute, La Jolla, California, CA 92037, USA.

Oncogene
|October 24, 2000
PubMed

Insights

Ras GTPases regulate cell adhesion. R-Ras variants with mutations affecting effector binding or prenylation impacted integrin function, but known R-Ras effectors were not critical for this regulation, suggesting novel mechanisms.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Ras GTP-binding proteins, including H-Ras and R-Ras, play crucial roles in cell signaling.
  • These proteins have opposing effects on integrin cell adhesion receptor regulation.
  • Understanding R-Ras interactions with downstream effectors is key to elucidating its role in cell adhesion.

Purpose of the Study:

  • To investigate the structural basis of R-Ras interactions with its downstream effectors.
  • To determine the role of specific R-Ras domains in regulating integrin function.
  • To identify novel mechanisms by which R-Ras influences cell adhesion.

Main Methods:

  • Analysis of R-Ras variants with mutations in the effector binding domain and C-terminal prenylation site.
  • Assessing the binding and activation of downstream effectors like PI 3-kinase, Ral-GDS, Raf-1, and Nore1.
  • Evaluating the impact of R-Ras mutations on integrin function in Chinese Hamster Ovary (CHO) cells.

Main Results:

  • Activation of PI 3-kinase and binding to Ral-GDS, Raf-1, and Nore1 were sensitive to mutations in the R-Ras effector binding domain.
  • Specific mutations in the effector binding loop and C-terminal prenylation motif impaired R-Ras-mediated regulation of integrin function in CHO cells.
  • The ability of R-Ras mutants to bind and activate known effectors did not correlate with their capacity to regulate integrin function, indicating these effectors are not critical for integrin activation in CHO cells.

Conclusions:

  • Known R-Ras effectors are not essential for regulating integrin activation in CHO cells.
  • The study provides insights into the structural requirements for R-Ras effector interactions.
  • Novel mechanisms by which R-Ras regulates cell adhesion are suggested, distinct from its known effector pathways.

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