The action of mercury on cell membranes.

The action of mercuric chloride and methyl mercuric chloride on the membrane lateral domain organization of bovine, equine, and canine erythrocytes was studied. Electron paramagnetic resonance (EPR) spectra of spin-labeled erythrocytes were analyzed with respect to their lateral domain structure. Continuous alteration of the membrane domain populations revealed that mercuric compounds affect the membrane via the evolution of toxic events in the cells.

Presence of a glycosylphosphatidylinositol lipid anchor on rose arabinogalactan proteins.

Arabinogalactan proteins constitute a class of plant cell surface proteoglycans with widespread occurrence and suggested functions in various aspects of plant growth and development, including cell proliferation, expansion, marking, and death. Previous investigations of subcellular fractions from suspension-cultured cells of "Paul's Scarlet" rose (Rosa sp.) have revealed extensive structural similarity between some soluble arabinogalactan proteins from the cell wall space and some plasma membrane-associated arabinogalactan proteins, thus inspiring the present investigation of the mechanism through which these inherently water-soluble molecules are held on the plasma membrane.

Spectroscopic characterization of specific phorbol ester binding to PKC-receptor sites in membranes in situ.

Electron paramagnetic resonance (EPR) spectra were measured for the spin labelled phorbol-12,13-diester [5,6]PA bound to membranes of the particulate fraction of mouse brain tissue rich in PKC receptors. [5,6]PA 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.

Transport and dynamics of molecules dissolved in maize root cortex membranes.

Translational diffusion of a fluorescent sterol probe was measured in the plasma membranes of protoplasts isolated from cortical cells of the primary root of maize seedlings. The apparent lateral diffusion coefficient was typically observed to be nearly insensitive to temperature, while the mobile fraction increased with increasing temperature. These fluorescence photobleaching recovery (FPR) measurements were compared with the electron paramagnetic resonance (EPR) spectra of the methyl ester of 13-doxyl palmitic acid in membranes of corn root tissue in situ.

Spin-labeled phorbol esters and their interactions with cellular membranes--V. Electron paramagnetic resonance of spin-labeled phorbol-12,13-diesters bound to their receptors in mouse brain particulate fraction.

The relatively small concentrations required for in vivo bioactivity of diterpene ester skin irritants and promoters (approximately 10 nmol per animal; approximately 10 nM in cell cultures) has discouraged studies of EPR spectra of bioactive, TPA-analogous, spin-labeled phorbol-12,13-diesters [(n,m)PA] bound to their membrane receptors, protein kinases C (PKC). To meet the requirements of present EPR spectrometers, particulate fraction from mouse brain containing at least 25 x 10(-12) mol of receptors/mg protein (PKC species) were employed together with certain (n,m)PA selected to give an optimal ratio of specific to non-specific binding. For selection and optimization of experimental conditions, a theoretical model was developed that considers all characteristic parameters of the system.