Hubbard A L, Ma A
J Cell Biol. 1983 Jan;96(1):230-9. doi: 10.1083/jcb.96.1.230.
Rat liver plasma membranes were isolated as presented in the preceding paper (Hubbard, A. L., D. A. Wall, and A. Ma., 1983, J. Cell Biol., 96: 217-229) and found to contain many filaments associated both with desmosomes along the lateral surface and with the cytoplasmic aspects of membranes comprising each of the three domains (lateral [LS], bile canalicular [BC] and sinusoidal [SF] ). Exposure of the plasma membranes to alkaline media (up to pH 11) resulted in loss of recognizable filaments without loss of domain morphology or membrane enzyme activities. Electrophoretic analysis of solubilized components from control and alkaline-extracted plasma membranes revealed that three major polypeptides present at 43, 52, and 56 kdaltons in the control had been released by alkaline treatment (pH 11) and could be quantitatively recovered in the supernate. The 43-kdalton component was identified as cytoplasmic actin by comparison of its tryptic 125I-peptide map to those of muscle (alpha) and brush border (beta, gamma) actins. The 52- and 56-kdalton polypeptides were identified as tonofilament components by their solubility properties and their ability to reassemble into 9.5-nm filaments from monomers present in an alkaline extract.
大鼠肝细胞膜的分离方法如前文所述（Hubbard, A. L., D. A. Wall, and A. Ma., 1983, J. Cell Biol., 96: 217 - 229），发现其含有许多细丝，这些细丝既与沿侧面的桥粒相关，也与构成三个结构域（侧面[LS]、胆小管[BC]和窦状隙[SF]）中每个结构域的膜的细胞质面相关。将质膜暴露于碱性介质（pH值高达11）中会导致可识别的细丝丢失，但结构域形态或膜酶活性没有损失。对对照和经碱性提取的质膜中溶解成分的电泳分析表明，对照中存在的43、52和56千道尔顿的三种主要多肽已通过碱性处理（pH 11）释放出来，并且可以在上清液中定量回收。通过将其胰蛋白酶125I - 肽图谱与肌肉（α）和刷状缘（β、γ）肌动蛋白的图谱进行比较，确定43千道尔顿的成分是细胞质肌动蛋白。52和56千道尔顿的多肽通过其溶解性以及从碱性提取物中存在的单体重新组装成9.5纳米细丝的能力被鉴定为张力丝成分。
