Membrane lipid-protein interactions modify the regulatory role of adenosine-deaminase complexing protein. A phase fluorometry study of a malignancy marker

Abraham H. Parola, Nurith Porat, Valeria R. Caiolfa, David Gill, Lutz A. Kiesow, Mathew Weisman, Stavanit Nemschitz, Dahlia Yaron, Karen Singer, Ethel Solomon

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The role of membrane lipid-protein interactions in malignant cell transformation was examined with adenosine deaminase (ADA) as a representative membrane protein. ADA's activity changes dramatically in transformed cells and accordingly it is a malignancy marker. Yet, the mechanisms controlling its variable activity are unknown. We undertook the spectroscopic deciphering of its interactions with its lipidic environment in normal and malignant cells. ADA exists in two interconvertible forms, small (45 KD) and large (210KD). The large form consists of two small catalytic subunits (SS-ADA) and a dimeric complexing protein ADCP. The physiological role of ADCP was not known either. Our studies were carried out at three levels: 1. Solution enzyme kinetics, 2. The interaction of SS-ADA with ADCP reconstituted in liposomes: effect of cholesterol and 3. Multifrequency phase modulation spectrofluorometry of pyrene-labeled SS-ADA bound to ADCP on the membranes of normal and RSV or RSV Ts68 transformed chick embryo fibroblasts. We found: 1. ADCP has an allosteric regulatory role on SS-ADA, which may be of physiological relevance: It inhibits SS-ADA activity at low physiological adenosine concentrations but accelerates deamination at high substrate concentration. 2. When reconstituted in DMPC liposomes, it retains SS-ADA activity (in its absence the activity is lost) and upon rigidification with cholesterol, a three fold increase in SS-ADA activity is attained, contrary to ADCP's regulatory activity when free of lipids.

Original languageEnglish
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
EditorsJoseph F. Lakowicz
PublisherPubl by Int Soc for Optical Engineering
Pages830-842
Number of pages13
Volume1204 pt 2
ISBN (Print)0819402451
Publication statusPublished - 1990
EventTime-Resolved Laser Spectroscopy in Biochemistry II - Los Angeles, CA, USA
Duration: Jan 15 1990Jan 17 1990

Other

OtherTime-Resolved Laser Spectroscopy in Biochemistry II
CityLos Angeles, CA, USA
Period1/15/901/17/90

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

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    Parola, A. H., Porat, N., Caiolfa, V. R., Gill, D., Kiesow, L. A., Weisman, M., Nemschitz, S., Yaron, D., Singer, K., & Solomon, E. (1990). Membrane lipid-protein interactions modify the regulatory role of adenosine-deaminase complexing protein. A phase fluorometry study of a malignancy marker. In J. F. Lakowicz (Ed.), Proceedings of SPIE - The International Society for Optical Engineering (Vol. 1204 pt 2, pp. 830-842). Publ by Int Soc for Optical Engineering.