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Adenosine deaminase in cell transformation. Biophysical manifestation of membrane dynamics

N Porat1, D Gill, A H Parola

  • 1Department of Chemistry, Ben-Gurion University of the Negev, Beer Sheva, Israel.

The Journal of Biological Chemistry
|October 15, 1988
PubMed

Insights

Cell transformation alters cell membranes, impacting adenosine deaminase (ADA) activity. This study uses phase fluorimetry to show changes in membrane protein interactions linked to cancer development.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Biophysics

Background:

  • Cell transformation, a hallmark of cancer, significantly alters cellular characteristics.
  • Adenosine deaminase (ADA) is an enzyme recognized as a malignancy marker, with decreased activity observed in transformed cells.
  • Chick embryo fibroblasts (CEF) transformed by Rous sarcoma virus exhibit reduced ADA activity.

Purpose of the Study:

  • To investigate the molecular mechanisms behind the reduced ADA activity in transformed cells.
  • To analyze the changes in the interaction between ADA and its membrane complexing protein (ADCP) during cell transformation.
  • To utilize phase fluorimetry to probe membrane dynamics and protein behavior in normal versus transformed CEF.

Main Methods:

  • Hybridization of fluorescently labeled SS-ADA with native ADCP on CEF.
  • Multifrequency differential phase fluorimetry to measure membrane protein dynamics.
  • Spectroscopic analysis to assess changes in membrane fluidity and protein mobility.

Main Results:

  • Cell transformation increased membrane fluidity and rotational mobility of ADCP.
  • Transformation led to reduced availability of ADCP for SS-ADA binding.
  • Spectroscopic data support the hypothesis of protein vertical sinking into the membrane lipid core.

Conclusions:

  • The complexing protein (ADCP) plays a regulatory role in ADA activity.
  • Changes in ADCP availability and mobility contribute to reduced ADA activity in transformed cells.
  • The findings suggest a model where protein sinking into the membrane influences enzyme function and cell state.

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