Clark C M, Goodlad G A
Biochim Biophys Acta. 1985 Oct 24;820(1):27-32. doi: 10.1016/0005-2736(85)90211-1.
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.
对正常大鼠肝脏以及携带Walker 256癌的大鼠肿大肝脏中不同质膜组分与肌动蛋白的关联进行了研究，此前已观察到携带Walker 256癌的大鼠肿大肝脏中细胞质肌动蛋白的聚合状态有所下降。通过脱氧核糖核酸酶I抑制试验估计，肌动蛋白分别约占富含侧向或胆小管区域的膜组分蛋白质的7%和3%，但在窦状隙组分中仅发现痕量。[3H]细胞松弛素B结合表明，侧向和胆小管组分中每毫克蛋白质分别存在20和13皮摩尔的高亲和力结合位点，而窦状隙组分中则没有。细胞松弛素B结合的解离常数对于侧向和胆小管组分而言约为1纳摩尔。通过对非离子去污剂不溶性残渣进行SDS/尿素/聚丙烯酰胺凝胶电泳得到的多肽图谱在所有三个组分中均不同，尽管包括肌动蛋白在内的一些蛋白质是胆小管和侧向区域的主要成分。肿瘤生长对这三个膜组分的肌动蛋白含量、高亲和力细胞松弛素B结合或多肽图谱没有影响。
