Plasma membranes isolated from bovine anterior pituitary gland are self-phosphorylated in the presence of [T-~~P]ATP by an endogenous protein kinase. Eighty per cent of protein kinase activity is solubilized by treatment of the plasma membranes with 1.0 N NH&l or 0.5% Triton X-100. The presence of latent protein kinase activity is shown by an approximately 50% increase of total enzymatic activi...

Rat liver plasma membranes were separated from other cellular membranes by affinity partitioning in an aqueous polymer two-phase system by using the lectin wheat-germ agglutinin covalently bound to dextran as the affinity ligand. In borate buffer the bulk of membranes partitioned in the poly(ethylene glycol)-rich top phase, whereas plasma membranes were pulled selectively into the dextran-rich ...

A cell-free assay monitoring lipid mixing was used to investigate the role of Ca2+ in neutrophil membrane-liposome fusion. Micromolar concentrations of Ca2+ were found to directly stimulate fusion of inside-out neutrophil plasma membrane enriched fractions (from neutrophils subjected to nitrogen cavitation) with liposomes (phosphatidylethanolamine:phosphatidic acid, 4:1 molar ratio). In contras...