[ PDB file ] [ PubMed link ]
p22HBP is a 22-kDa mammalian protein that is highly upregulated during erythroid development, and appears to be a target gene of GATA-1. Its function is currently unknown, although it has been reported to bind to a range of different porphyrins, suggesting a role in heme biosynthesis. We have determined the structure of p22HBP and used HSQC titration data to map its porphyrin binding site. Interestingly, our structure reveals that p22HBP has structural (but not sequence) homology to a bacterial multi-drug resistance protein BmrR that functions by binding to a variety of small hydrophobic drug molecules.