E Schematic structure of the humanPOGLUT1protein, which contains a signal peptide (SP), a CAP10 domain, and a Lys-Asp-Glu-Leu (KDEL)-like endoplasmic reticulum retention signal. D233E is located in the CAP10 domain (arrow), close to the predicted ERD catalytic motif (asterisk). Alignment of amino acids flanking the mutated aspartic acid from POGLUT1 orthologs indicates evolutionary conservation of D233 in vertebrates (open arrowhead). Black boxes denote similarity of amino acid residues. 