Higgins J A
J Cell Sci. 1976 Oct;22(1):173-97. doi: 10.1242/jcs.22.1.173.
During proliferation of smooth endoplasmic reticulum (SER) induced by phenobarbital the specific activity of acyltransferases of the smooth microsomes increases, there is a transient rise in the phospholipid/protein ratio of these membranes, and an increased incorporation of [14C]glycerol into smooth-membrane phospholipid. Microsomes separated into subfractions on 2 gradients exhibited a heterogeneous distribution of these characteristics, indicating a non-uniform distribution of the site of phospholipid synthesis in the ER under these conditions. Cytochemical localization of acyltransferases on whole liver and smooth and rough microsomes confirmed this heterogeneity, and indicated that the distribution of this activity was not restricted to any morphologically distinct site in the ER of the intact cell. After 4 days of phenobarbital treatment the increased membrane is restricted to lighter subfractions and is similar in distribution to that of increased acyltransferase activity. These results indicate that the synthesis of membrane phospholipid and the growth of the SER in response to phenobarbital is not uniform but occurs at randomly dispersed sites in the SER while proteins may be added preferentially at these sites resulting in a final uniform distribution.
在苯巴比妥诱导滑面内质网（SER）增殖过程中，滑面微粒体酰基转移酶的比活性增加，这些膜的磷脂/蛋白质比值出现短暂升高，且[14C]甘油掺入滑面膜磷脂的量增加。在两个梯度上分离成亚组分的微粒体显示出这些特征的异质性分布，表明在这些条件下内质网中磷脂合成位点分布不均一。酰基转移酶在全肝以及滑面和粗面微粒体上的细胞化学定位证实了这种异质性，并表明该活性分布并不局限于完整细胞内质网中任何形态学上不同的位点。苯巴比妥处理4天后，增加的膜限于较轻的亚组分，其分布与增加的酰基转移酶活性的分布相似。这些结果表明，响应苯巴比妥的膜磷脂合成和滑面内质网生长并不均匀，而是发生在滑面内质网中随机分散的位点，而蛋白质可能优先添加到这些位点，从而导致最终的均匀分布。
