The in vitro-to-in vivo extrapolation (IVIVE) methods for predicting the hepatic clearance (CL) of drugs based on microsomal or hepatocyte data have certainly advanced; however, there is still place improving extrapolations from vitro assays containing no plasma proteins. Accordingly, a discussion whether free drug hypothesis an albumin (ALB)-mediated uptake phenomenon best scaling method. Ther...

Band 3, the anion transport protein of the erythrocyte membrane, exists in the membrane as a mixture of dimers (B3D) and tetramers (B3T). The dimers are not linked to the skeleton and constitute the free mobile band 3 fraction. The tetramers are linked to the skeleton by their interaction with ankyrin. In this report we have examined the temporal synthesis and assembly of band 3 oligomers into ...

Rat liver microsomes contain an enzyme that catalyzes the isomerization of the nuclear double bond of steroids from the 8(9) position to the 7(8) position. The enzyme is most active with zymosterol, 5alpha-cholesta-8,24-dien-3beta-ol, which is a precursor of cholesterol. Properties of the microsomal isomerase have now been studied, and preliminary data are reported on both regulation of enzymic...

Free and membrane-bound polyribosomes were isolated from the forebrain of actively myelinating 24-day-old rats. The poly(A)+ RNA (polyadenylated RNA) extracted from both fractions was translated in vitro in reticulocyte lysates [Hall & Lim (1981) Biochem. J. 196. 327-336] in the presence or absence of a heterologous microsomal membrane fraction from dog pancreas. The rat myelin basic proteins s...

Experiments were designed to assess the effect of cholesterol feeding, with or without high levels of either saturated (coconut oil) or unsaturated (sunflower-seed oil) fat on the fatty acid composition of hepatic microsomal membrane lipids, as well as on the activities of several membrane-bound enzymes of cholesterol synthesis and metabolism. Administration of 2% (w/w) cholesterol in the rat d...

Protein disulphide-isomerase (PDI) activity was not detectable in freshly prepared rat liver microsomes (microsomal fraction), but became detectable after treatments that damage membrane integrity, e.g. sonication, detergent treatment or freezing and thawing. Maximum activity was detectable after sonication. Identical latency was observed in microsomes prepared by gel filtration and in those pr...