Figure 10.8.

A summary of mutations of the SLC37A4 gene that affect G6P uptake activity. The G6PT protein is shown embedded in the ER membrane. The 10-helical trans-membrane domains of G6PT are marked as boxes H1 to H10, the cytoplasmic loops are marked as C1 to C4, and the luminal loops are marked as L1 to L4. Mutations that have been shown to obliterate G6PT activity are listed without parentheses after. Mutants that retain residual activity are listed with the percent of wild-type transport activity retained noted in parentheses. The three naturally occurring signature motif mutations (p.Q133P, p.A148V, and p.G149E) identified to date in GSD-Ib patients are shown in boldface. Mutations that have not been functionally characterized are boxed. Mutations that have been characterized by both cell-based assays and proteoliposomal assays are shown in italic.