Gärtner J, Chen W W, Kelley R I, Mihalik S J, Moser H W
Kennedy Institute for Handicapped Children, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Pediatr Res. 1991 Feb;29(2):141-6. doi: 10.1203/00006450-199102000-00007.
The primary genetic defect of Zellweger syndrome may be related to defective synthesis or impaired import of peroxisomal proteins. We analyzed the presence and measured the abundance of the 22-kD peroxisomal integral membrane protein (PMP) in patients with Zellweger syndrome. We determined the intracellular localization of the 22-kD PMP and compared it with the localization of a peroxisomal 44-kD thiolase precursor protein. The 22-kD PMP was quantified by immunoblot analyses in liver tissue (n = 7 patients). Immunoblot signals were evaluated using transmission photometry. The intracellular localization of the 22-kD PMP and the peroxisomal 44-kD thiolase precursor protein were determined by immunoblot analyses on fibroblast subcellular fractions prepared by Nycodenz (n = 5 patients) or sucrose density gradient centrifugation (n = 2 patients). The 22-kD PMP was present and associated with membrane fractions in all patients. Its abundance varied in patients as compared with normal human liver controls. The 22-kD PMP was located in subcellular membrane fractions having a lower density than normal peroxisomes or mitochondria. Using two different gradient techniques, the 22-kD PMP and the peroxisomal 44-kD thiolase precursor protein were found in the same low-density gradient fractions. These results suggest that in Zellweger syndrome peroxisome-like elements containing both the 22-kD PMP and a 44-kD thiolase precursor protein are formed. Globally defective synthesis or import of peroxisomal proteins is therefore unlikely to be the primary genetic defect in the patients we studied.
脑肝肾综合征的主要遗传缺陷可能与过氧化物酶体蛋白合成缺陷或输入受损有关。我们分析了脑肝肾综合征患者中22-kD过氧化物酶体整合膜蛋白（PMP）的存在情况并测定了其丰度。我们确定了22-kD PMP的细胞内定位，并将其与过氧化物酶体44-kD硫解酶前体蛋白的定位进行比较。通过免疫印迹分析对肝组织（n = 7例患者）中的22-kD PMP进行定量。使用透射光度法评估免疫印迹信号。通过对用Nycodenz（n = 5例患者）或蔗糖密度梯度离心法（n = 2例患者）制备的成纤维细胞亚细胞组分进行免疫印迹分析，确定22-kD PMP和过氧化物酶体44-kD硫解酶前体蛋白的细胞内定位。所有患者均存在22-kD PMP并与膜组分相关。与正常人类肝脏对照相比，其丰度在患者中有所不同。22-kD PMP位于密度低于正常过氧化物酶体或线粒体的亚细胞膜组分中。使用两种不同的梯度技术，在相同的低密度梯度组分中发现了22-kD PMP和过氧化物酶体44-kD硫解酶前体蛋白。这些结果表明，在脑肝肾综合征中，形成了含有22-kD PMP和44-kD硫解酶前体蛋白的类过氧化物酶体元件。因此，过氧化物酶体蛋白的整体合成缺陷或输入缺陷不太可能是我们所研究患者的主要遗传缺陷。
