Functional analysis of mutations in the glucose-6-phosphate transporter that cause glycogen storage disease type Ib

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• 作者：Shih-Yin Chen ; Chi-Jiunn Pan ; Soojung Lee ; Wentao Peng ; Janice Y. Chou
• 关键词：Glycogen storage disease type Ib ; Glucose-6-phosphate transport ; Phosphate transport ; Proteoliposomes ; Mutation analysis
• 刊名：Molecular Genetics and Metabolism
• 出版年：2008
• 出版时间：December 2008
• 年：2008
• 卷：95
• 期：4
• 页码：220-223
• 全文大小：185 K

文摘

The glucose-6-phosphate transporter (G6PT) deficient in glycogen storage disease type Ib is a phosphate (P_i)-linked antiporter capable of G6P: P_i and P_i:P_i exchanges. We previously characterized G6PT mutations by measuring G6P uptake activities in microsomes co-expressing G6PT and glucose-6-phosphatase-α. Here we report a new assay, based on reconstituted proteoliposomes carrying only G6PT, and characterize G6P and P_i uptake activities of 23 G6PT mutations. We show that co-expression and G6PT-only assays are equivalent in measuring G6PT activity. However, the p.Q133P mutation exhibits differential G6P and P_i transport activities, suggesting that characterizing G6P and P_i transport activities of G6PT mutations may yield insights to this genetic disorder.