Commentary on Gressel's review

Transgenic Research -     

Separation and Partial Characterization Of Rat Liver Cell Membrane Components

The objectives of this research were to separate and partially characterize the components of rat liver cell plasma membranes. The plasma membranes of liver cells obtained from normal Wistar male rats were isolated using density gradients. The purified membrane was then solubilized in phenol-urea-acetic acid and gel electrophoresis was performed on the solubilized membrane components. Samples of the eluate collected following preparative gel electrophoresis were phosphorus positive-ninhydrin positive; phosphorus negative-ninhydrin positive; phosphorus po6itive-ninhydrin negative; and phosphorus negative-ninhydrin negative. The amino acid analyses showed that the proteins of the separated components were different and that no one component contained more than 6% of the total membrane protein. Liver cell plasma membranes contain components that differ from those of red blood cell plasma membranes. These components can be further divided into subgroups of proteins, i.e., phospholipoproteins and protein alone. The concept of a group of proteins composing the membrane is extended to one of various subgroups on the basis of their different affinity for lipid.     

Polyethylene glycol-enhanced nephelometric quantification of bovine submaxillary mucin with Helix pomatia lectin

A new principle for quantification of intact mucin has been developed. The method is reproducible, simple, and sensitive at the submicrogram level and can be performed within an hour. The procedure involves incubation of mucin (bovine submaxillary mucin) and polyethylene glycol with the lectin from the snail Helix pomatia and the complexes formed are quantitated by nephelometry. Polyethylene glycol was found to enhance the affinitin reaction in a dose-dependent fashion. Increasing concentrations of acetate or citrate led to decreasing light scattering of the polyethylene glycol--bovine submaxillary mucin--H. pomatia lectin reaction mixture. Results from displacement studies with N-acetyl-galactosamine suggest that H. pomatia lectin may contain an allosteric type of regulatory site. The quantitative results obtained with bovine submaxillary mucin using the new method correlated well with those obtained with an established method for neuraminic acid determination after neuraminidase digestion (R = 0.969, P less than 0.001; n = 24).