Williams J C, Weinstein D B, Miller A L, Steinberg D
Biochem J. 1982 Jan 15;202(1):183-90. doi: 10.1042/bj2020183.
Skin fibroblast cultures from patients with I-cell disease (mucolipidosis II) are characterized by multiple lysosomal enzyme deficiencies The present studies deal with the consequences of these deficiencies with respect to the metabolism of plasma low-density lipoproteins. Degradation of the protein moiety was defective in I-cells compared with control cells, but the binding and internalization of low density lipoprotein were much less affected. Measurements of low-density lipoprotein degradation in homogenates demonstrated directly for the first time a deficiency of acid proteinase activity in I-cell fibroblasts. Comparison of results in 6-h incubations with those in 24-h incubations showed accumulation of intracellular low-density lipoprotein in I-cell fibroblasts and an accelerating rate of degradation, possibly attributable to intracellular accumulation of low-density lipoprotein substrate. The significance of these findings with respect to low-density lipoprotein metabolism in vivo is discussed.
患有I细胞病（粘脂贮积症II型）患者的皮肤成纤维细胞培养物的特征是多种溶酶体酶缺乏。目前的研究探讨了这些缺乏对血浆低密度脂蛋白代谢的影响。与对照细胞相比，I细胞中蛋白质部分的降解存在缺陷，但低密度脂蛋白的结合和内化受影响较小。对匀浆中低密度脂蛋白降解的测量首次直接证明了I细胞成纤维细胞中酸性蛋白酶活性的缺乏。将6小时孵育结果与24小时孵育结果进行比较，发现I细胞成纤维细胞中细胞内低密度脂蛋白积累，且降解速率加快，这可能归因于细胞内低密度脂蛋白底物的积累。文中讨论了这些发现对体内低密度脂蛋白代谢的意义。
