Studies on rat liver plasma membrane. Altered protein and phospholipid metabolism after injection of D-galactosamine.
1. The metabolism of protein and phospholipid in rat liver plasma membranes isolated by the method of Neville [(1960) J. Biophys. Biochem. Cytol. 8, 413-422] was investigated 3 and 6 h after the injection of D-galactosamine in vivo. During this time, all the biochemical and morphological alterations associated with hepatitis developed. 2. After the injection of D-galactosamine the concentration of sphingomyelin in the plasma membrane decreased to below 60% of the control values. 3. The activity of 5'-nucleotidase (EC 3.1.3.5), which has been purified as a sphingomyelin-protein complex, decreased in the total homogenate as well as in the plasma-membrane fraction of livers of rats treated with galactosamine, to about 60% of the control values. 4. Protein synthesis, as measured by the incorporation of [14C]leucine into plasma membranes, was decreased to 45% of that of the controls. However, only small differences were observed in the amino acid composition of the plasma membrane after D-galactosamine treatment. 5. The protein composition of the plasma membranes was determined by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The results showed a change from low- to high-molecular-weight proteins after the injection of galactosamine. 6. These results demonstrate different metabolic processes of the plasma membrane altered during the induction of galactosamine hepatitis.
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects*; D005260:Female; D005688:Galactosamine / Q000494:pharmacology*; D008099:Liver / Q000187:drug effects*; D009708:Nucleotidases / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism*; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D013109:Sphingomyelins / Q000378:metabolism
D010743:Phospholipids; D011506:Proteins; D013109:Sphingomyelins; D005688:Galactosamine; D009708:Nucleotidases; D000469:Alkaline Phosphatase