Plasma membrane associated actin in liver of normal and tumour-bearing rats.
A study was made of the association of actin with different plasma membrane fractions from liver of normal rats and from the enlarged liver of rats bearing a Walker 256 carcinoma where a decrease in the state of polymerisation of cytoplasmic actin has been previously observed. As estimated by the DNAase I inhibition assay, actin constituted approx. 7% and 3%, respectively, of the protein of membrane fractions enriched in lateral or bile-canalicular domains, but only trace amounts were found in the sinusoidal fraction. [3H]Cytochalasin B binding indicated the presence of 20 and 13 pmol of high-affinity binding sites per mg protein in lateral and bile-canalicular fractions, but none in the sinusoidal. Kd for cytochalasin B binding was of the order of 1 nM for lateral and bile-canalicular fractions. Polypeptide profiles obtained by SDS/urea/polyacrylamide gel electrophoresis of non-ionic detergent-insoluble residues differed for all three fractions although some proteins, including actin, occurred as major components of both bile-canalicular and lateral regions. Tumour growth had no effect on the actin content, high-affinity cytochalasin B binding or polypeptide profiles of the three membrane fractions.
D000199:Actins / Q000378:metabolism*; D000818:Animals; D001648:Bile Canaliculi / Q000378:metabolism; D001665:Binding Sites; D002279:Carcinoma 256, Walker / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003571:Cytochalasin B / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000037:antagonists & inhibitors; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D008099:Liver / Q000378:metabolism*; D008970:Molecular Weight; D009368:Neoplasm Transplantation; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution
D000199:Actins; D003571:Cytochalasin B; D003850:Deoxyribonuclease I