Figure 1

Structural diagram of intact UGT1A1 and UGT1A1-p.Q331X. Most of the UGT1A1 enzyme localizes within the ER lumen except for the carboxyl-terminus, which remains in the cytoplasm. Within the intra-luminal part of the molecule, 152–180 amino acids were proposed to be a trans-membrane region (TR) using the RAOARGOS computer program. In UGT1A1-p.Q331X a C to T transition at nucleotide 991 results in the generation of a premature stop codon. In this mutant, the N-terminal region is normal, containing a signal peptide (SP) and a dimerization domain (DD), but the C-terminal region, which contains the catalytic region (CR), trans-membrane region (TR) and the ER retention signal sequence (ES), is deleted. A full color version of this figure is available at the Journal of Human Genetics journal online.