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Updated: Apr 3, 2026

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells
10:27

Spatio-Temporal Manipulation of Small GTPase Activity at Subcellular Level and on Timescale of Seconds in Living Cells

Published on: March 9, 2012

11.3K

Ras p21 proteins with high or low GTPase activity can efficiently transform NIH/3T3 cells

J C Lacal, S K Srivastava, P S Anderson

    Cell
    |February 28, 1986
    PubMed

    Insights

    Ras p21 mutants can gain transforming properties without reduced GTPase activity. This study shows efficient transformation can occur through alternative mechanisms, challenging previous assumptions about ras oncogene activation.

    Area of Science:

    • Molecular Biology
    • Oncology
    • Cell Biology

    Background:

    • Ras p21 proteins are key regulators of cell signaling.
    • Reduced GTPase activity of ras p21 mutants is often linked to oncogenic transformation.
    • The precise mechanisms driving ras-mediated transformation require further elucidation.

    Purpose of the Study:

    • To investigate the relationship between in vitro GTPase activity and transforming properties of ras p21 mutants.
    • To determine if decreased GTPase activity is a universal requirement for ras p21-driven cellular transformation.

    Main Methods:

    • In vitro GTPase activity assays were performed on normal and mutant H-ras p21 proteins.
    • Bacterially expressed normal H-ras p21 and various p21 mutants were microinjected into NIH/3T3 cells.
    • Cellular morphologic alterations and DNA synthesis were assessed post-microinjection.
    • Transforming activity of mutants expressed in eukaryotic vectors was compared to normal H-ras.

    Main Results:

    • Mutants H-ras p21-[Lys12-Ala59] and H-ras p21-[Arg12-Thr59] showed significantly lower in vitro GTPase activity compared to normal H-ras p21-[Gly12-Ala59] and H-ras p21-[Gly12-Thr59].
    • Low concentrations of p21 mutants induced NIH/3T3 cell morphologic changes and DNA synthesis, unlike normal p21.
    • Mutant ras p21 proteins exhibited transforming activity at least 100-fold greater than the normal H-ras gene.

    Conclusions:

    • Efficient transforming properties of ras p21 proteins can be activated independently of reduced in vitro GTPase activity.
    • These findings suggest alternative pathways for ras oncogene activation and transformation.
    • The study challenges the paradigm that diminished GTPase function is essential for ras-driven oncogenesis.

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