Human Hexose-6-phosphate Dehydrogenase (Glucose 1-Dehydrogenase) Encoded at 1p36: Coding Sequence and Expression

ABSTRACT: Using the published protein sequence from a rabbit microsomal glucose-6-phosphate dehydrogenase G6PD we have isolated and sequenced a cDNA clone coding for its human equivalent, which is also known as hexose-6-phosphate dehydrogenase (H6PD) and glucose dehydrogenase. The corresponding genomic sequence is in the databases enabling its localization to chromosome 1p36. The gene spans 37 kb and consists of 5 exons, the fifth of which codes for more than half of the 89kDa protein. The first intron is a 10kb insertion in the 5′ untranslated sequence. The predicted mRNA has an exceptionally long (6.5kb) 3′ untranslated sequence. The predicted protein shows extensive homology with X-linked G6PD, suggesting the two genes share a common ancestor but no intron positions are conserved between the two genes suggesting the gene duplication was an ancient event. The C-terminal portion of the protein is not homologous with G6PD but shows limited homology with proteins of unknown function found throughout evolution and encoded next to G6PD in various micro-organisms. Intriguingly this C-terminal portion has some homology with the N-terminal sequence ofPlasmodium falciparumG6PD.