Membrane-phorbol ester interactions monitored by circular dichroism.
The interaction of phorbol 12,13-dibutyrate (PDBu), 12-O-retinoylphorbol 13-acetate (RPA) and 12-O-tetradecanoylphorbol 13-acetate (TPA) with L-alpha-phosphatidylserine-containing small unilamellar vesicles or erythrocyte ghosts was monitored by circular dichroism (CD). No change in the CD spectra of PDBu was observed upon binding, while RPA and TPA spectra were slowly affected by the interaction. The changes in RPA and TPA spectra were assigned to the embedding of these molecules in the membrane bilayers. In the presence of 10(8) cells/ml, after one minute incubation, about 2 to 5% of the amount of phorbol ester added is embedded in the membrane. It is suggested that either phorbol esters entering the membrane is not a prerequisite for protein kinase C activation or the amount of phorbol esters necessary to activate protein kinase C is very small.
Frézard
F
F
Laboratoire de Chimie Bioinorganique (UA CNRS 198), UFR Biomédicale, Université Paris Nord, Bobigny, France.
Garnier-Suillerot
A
A
Bolard
J
J
Castagna
M
M
D002942:Circular Dichroism; D004789:Enzyme Activation; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D008081:Liposomes / Q000378:metabolism*; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D010703:Phorbol Esters / Q000378:metabolism*; D010718:Phosphatidylserines / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D013057:Spectrum Analysis; D013755:Tetradecanoylphorbol Acetate / Q000378:metabolism
D008081:Liposomes; D010703:Phorbol Esters; D010718:Phosphatidylserines; D015240:Phorbol 12,13-Dibutyrate; C032974:12-O-retinoylphorbol-13-acetate; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate