Author/Editor		Svetek, J; Schara, M; Pečar, S; Hergenhahn, M; Hecker, E
Title		Spectroscopic characterization of specific phorbol ester binding to PKC-receptor sites in membranes in situ
Type		članek
Source		Carcinogenesis
Vol. and No.		Letnik 16, št. 10
Publication year		1995
Volume		str. 2589-92
Language		eng
Abstract		Electron paramagnetic resonance (EPR) spectra were measured for the spin labelled phorbol-12,13-diester Š5,6ĆPA bound to membranes of the particulate fraction of mouse brain tissue rich in PKC receptors. Š5,6ĆPA is a bioactive derivative of the potent tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), carrying the spin label in a doxyl group in position 7' of the 12-O-tetradecanoyl residue. A mathematical model based on special algorithms (Griffith, O.H. and Jost, P.C. Spin labeling: theory and applications, 1976) allows a satisfactory reconstruction of the experimental spectrum. It reveals that in the experimental spectrum the signal from the Š5,6ĆPA molecules bound non-specifically to the lipid bilayer of the membranes is superimposed by the signal of Š5,6ĆPA molecules bound specifically, i.e. to the active site of PKC (approximately 10 percent of total EPR signal intensity). Moreover, interpretation of spectral parameters indicates that in Š5,6ĆPA molecules bound specifically the tetradecanoyl chain exhibits a larger motional freedom compared to that in Š5,6ĆPA bound non-specifically. These new findings are in accordance with views featured independently by two recent molecular models of interaction of PKC with cellular membranes (8,9).
Descriptors		BRAIN CARCINOGENS PROTEIN KINASE C RECEPTORS, CELL SURFACE TETRADECANOYLPHORBOL ACETATE BINDING SITES CELL MEMBRANE ELECTRON SPIN RESONANCE SPECTROSCOPY KINETICS LIPID BILAYERS MATHEMATICS MICE MODELS, THEORETICAL SPIN LABELS