Glycogen Storage Disease Type 1b: Disorder of Microsomal membrane Transport.

糖原储存病（GSD） 1b型患者体外无葡萄糖-6-磷酸酶缺陷，但临床表现与GSD la型患者相对难以区分。基于葡萄糖-6-磷酸酶活性在新鲜肝脏匀浆中高度潜伏的发现，我们发现GSD 1b的一个基本缺陷位于微粒体膜上的G6P运输系统。在本研究中，我们建立了一种研究微粒体摄取G6P的方法。在对照组中观察到微粒体对G6P的显著摄取。相反，GSD 1b患者对G6P的摄取可以忽略不计。这些发现为G6P特异性转运系统存在于人微瘤膜中提供了直接证据，GSD 1b是由于G6P转运系统的缺陷引起的。目前，鉴定GSD 1型变异的缺陷位点需要对G6P和焦磷酸盐磷酸水解酶进行检测，同时使用未重复的和中断的微粒体制备。为了计算“完整微粒体”的理论磷酸水解酶活性，测定M6P磷酸水解酶活性是必不可少的。我们开发了显微方法来测量所有三种磷酸水解酶活性在未处理的和被破坏的制剂，这可以应用于针活检标本。采用该系统检测G6Pase系统的方法，对另外3例GSDlb患者进行了检测。中性粒细胞减少症是GSD lb的一个显著特征。我们研究了中性粒细胞代谢异常与G6P转位酶缺陷之间的关系。研究了3例临床和酶学结果不同的受刺激的中性粒细胞的代谢爆发。G6P转位酶残留活性为零的2例兄弟姐妹未能表现出正常的单磷酸己糖分流活性刺激。刺激。而G6P转位酶活性部分缺失的成人患者在刺激后出现正常的呼吸爆发。这些发现使我们对中性粒细胞中G6P转位酶的存在及其功能进行了推测。少

patients with glycogen storage disease (GSD) type 1b have no defect of glucose-6-phosphatase in vitro, but the clinical findingsare relatively indistinguishable from those of GSD type la. We revealed that a basic defect in GSD 1b was located in the G6P transport system od the microsomal membrane,based on the findings that the glucose-6-phosphatase activity was highly latent in the fresh liver homogenates. In this study, we deceloped a method to investigate th uptake uptake G6P by microsomes. A significant uptake of G6P by microsomes was observed in controls. On the contrary, the patient with GSD 1b showed a negligble uptake of G6P. These findings provide direct evidence the a G6P-specific transport system exists in the human microzomal membrane and that GSD 1b is due to a defect of the G6P transport system. At present the identification of the locus of the defect in the variants of GSD type 1 requires an assay for both the G6P and the pyrophosphate phosphohydrolase using both unterated … More and disrupted preparations of microsomes. The determination of M6P phosphohydrolase activity is essent-ial in order to calculate the theoretical phsphohydrolase activities for the"intact microsomes". We developed micromethods to measure all three phosphohydevlase activities in both the untreated and the the disrypted prepare-tions, which can be applied to needle biopsy specimens. Using thissystematic assay method for G6Pase system, add-itional 3 patients with GSDlb were examined. Neutropenia is a distinctive feature of GSD lb. We investigated the relationship between metabolic abnormalities in the neutrophil and the defect of G6P translocase. The metabo-lic burst in stimulated neutrophils was investigated in 3 patientswith differnt clinical and enzymatic findings. The two siblings who had on residual activity of G6P translocase failed to show the normal stimulation of hexose monophosphata shunt activity with various. stimuli. On the hand, the adult patient with the partial defici-ency of G6P translocase activity showed normal respiratory burst after stimulation. These findings led us to spe-culate on the presence of G6P translocase in neutrophils and its function. Less