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Enzymatic hydrolysis of the pyrophosphate bond of CDP-diglyceride (CDP-DG), previously shown to occur in bacteria, is demonstrable in mammalian tissues. Activity was enriched in a lysosomal fraction obtained from guinea pig cerebral cortex and was purified 92-fold relative to the homogenate by a combination of XM-300 ultrafiltration and DEAE-cellulose column chromatography. When incubated with CDP-dipalmitin, the purified enzyme produced stoichiometric amounts of CMP and phosphatidate. dCDP-DG served as a substrate, while ADP-DG was an inhibitor, as were 5'-AMP and 5'-dAMP. CDP-DG hydrolysis was not affected by the presence of excess amounts of CDP-choline, CDP-glycerol, sodium pyrophosphate, or cyclic 3',5'-AMP.

We report the use of three classes of variants from the long-established, malignantly transformed LM cell line to demonstrate that the apparent mobility of cell surface receptors need not be dependent on the expression of the transformed phenotype in vitro.

Antibodies to a protein present in the cell envelope of Hydrogenomonas facilis agglutinate many gram-negative bacteria and a few gram-positive bacteria. Immunodiffusion studies of extracts from the various organisms tested indicate the presence of components sharing antigenic determinants with the cell envelope protein in all bacteria which can be agglutinated and a few that cannot. Cross-reacting components were not detected in extracts of Mycoplasma laidlawii, Anacystis nidulans, and several eukaryotic organisms.

Intact cells of Pseudomonas facilis contain one major molecular weight class of protein that is exposed at the cell surface as revealed by lactoperoxidase-catalyzed iodination with (125)I. All molecular weight classes of protein in derived cell envelope preparations are apparently saturated by iodination by lactoperoxidase after prolonged sonic treatment. The molecular weight of the predominantly exposed protein in intact cells is approximately 16,000, which is the minimal molecular weight of a cell envelope protein that precipitates as a complex with phospholipid from extracts of P. facilis. The isolation of labeled phospholipoprotein (PLP) after labeling intact cells with (125)I corroborates previous experiments which suggested a surface location for the protein portion of the phospholipoprotein (P(PLP)). Solvent extraction of cells and immunological evidence, including studies with ferritin-coupled antibodies, indicate that P(PLP) is located at the cell surface and may also be within the cell envelope. These experiments suggest that P(PLP) is the major cell surface protein in P. facilis.

Hydrogenomonas facilis grown heterotrophically on fructose with very low aeration eventually ceased to divide and produced elongated forms. Short forms were obtained from fructose-grown long forms by increasing the availability of oxygen to the organisms. A phospholipoprotein, the protein moiety of which is known to be present in the cell envelope, precipitated upon lowering the ionic strength of extracts from cells in the earlier stages of elongation (i.e., in the middle and late log phase of growth). The maximal yield of the protein moiety of the phospholipoprotein precipitate (i.e., grams of protein/grams of soluble protein x 100) was 2%. Poly-beta-hydroxybutyric acid accumulated as growth on fructose progressed, the accumulation being more marked with lower aeration.