The distribution of the components of mixed-function oxidase between the rough and the smooth endoplasmic reticulum of liver cells.
Mixed-function oxidase activity, when measured by the N-demethylation of ethylmorphine or the hydroxylation of aniline, is significantly higher in the smooth hepatic endoplasmic reticulum than in the rough. In the rabbit the smooth membrane/rough membrane activity ratios are significantly greater than 1 whether the activities are expressed per g. of liver (ratio 5), per mg. of protein (ratio 3-5), per mug. of phospholipid phosphorus (ratio 2), per unit of cytochrome P-450 (ratio 1.7) or per unit of NADPH-cytochrome c reductase activity (ratio 2). On the other hand, if the activities are normalized to the NADPH-cytochrome P-450 reductase, there is no significant difference between the rough and smooth membranes. These results suggest that, in the rabbit, the rate-limiting step is the reduction of cytochrome P-450. In contrast, in the rat the difference in activities can be explained by differences in the concentration of cytochrome P-450.
D000814:Aniline Compounds / Q000378:metabolism; D000818:Animals; D003580:Cytochromes / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000201:enzymology*; D066298:In Vitro Techniques; D008099:Liver / Q000201:enzymology*; D008297:Male; D008861:Microsomes / Q000201:enzymology; D009019:Morphinans / Q000378:metabolism; D010088:Oxidoreductases / Q000032:analysis*; D011817:Rabbits; D051381:Rats
D000814:Aniline Compounds; D003580:Cytochromes; D009019:Morphinans; D010088:Oxidoreductases