A method is described for the localization and characterization of phospholipases A1 and A2 (EC3.1.1.4) in Krebs II ascites cells, particularly in the plasma membranes. Cells were lysed with a Dounce homogenizer in an isotonic sucrose medium. Plasma membranes sediment with mitochondria and lysosomes during subcellular fractionation and are finally isolated on a continuous sucrose gradient. The ...

Specific quantitative techniques have been used to measure the cytoplasmic estradiol-binding protein (EBP) in human mammary carcinoma tissue specimens. Sucrose gradient centrifugation reveals EBP to sediment at 8S and 4S. Variable quantities of non-specific estradiol binding occurs in the 4S region of the sucrose gradient necessitating controls to insure specificity of the estradiol protein int...

The genome of infectious pancreatic necrosis virus consists of two segments of dsRNA, in equimolar amounts, with molecular weights of 2.5 X 10(6) and 2.3 X 10(6) daltons, as determined by polyacrylamide gel electrophoresis and autoradiography. The viral RNA was resistant to ribonuclease, and in sucrose gradient it co-sedimented at 14S with RNase resistant RNA from virus infected cells. Upon den...

The presynaptic terminal vesicle population of Torpedo electric organ is heterogeneous in size, consisting of two prominent subpopulations that comprise 80% of the total. The use of standard iso-osmotic sucrose gradients with zonal centrifugation to isolate vesicle fractions that co-localize with the acetylcholine (ACh) peak results in the recovery of: (1) 10% of the total estimated vesicle pop...

The degree of solubilization of pig lymphocyte plasma membrane by sodium deoxycholate was determined at a variety of temperatures and detergent concentrations. Approx. 95% of the membrane protein was soluble in 2% deoxycholate at 23 degrees C. Some of the biological activities of the membrane survived this treatment. The leucine beta-naphthylamidase activity was more readily soluble than the 5'...

A Sepharose 4B chromatographic method for purification of retroviruses is described which was less time consuming, increased purified virus yields, conserved viral glycoprotein, and increased recovery of biological infectivity in comparison with conventional sucrose gradient ultracentrifugation techniques.

Feline leukemia virus from tissue culture fluids was concentrated 100 times by continuous-flow molecular filtration. Virus concentrates retained 100% of their original infectivity. Further purification was accomplished by a single sucrose density gradient centrifugation.

The isopycnic equilibrium of [131J]albumin digesting particles from mouse liver homogenates occurs, in a sucrose gradient, at a density 1.25, and it does not change with time after albumin injection (5 to 300 minutes).

Assimilates enter developing wheat grains via a strand of phloem extending along the crease region of the grain. After phloem unloading, they move several hundred micrometers before being released into the endosperm cavity, from which they are absorbed by the developing endosperm. Extraphloem assimilate pools in the maternal tissue of the crease, therefore, play a central role in post-phloem tr...

Sucrose transport from the apoplasm, across the plasma membrane, and into the symplast is critical for growth and development in most plant species. Phloem loading, the process of transporting sucrose against a concentration gradient into the phloem, is an essential first step in long-distance transport of sucrose and carbon partitioning. We report here that a soybean 62-kD sucrose binding prot...