p22HBP, also known as HEBP1 (heme binding protein 1), HBP or HEBP, is a 189 amino acid intracellular tetrapyrrole-binding protein that assists in prevention of cellular toxicity by removing free porphyrinogens from the cell. Existing as a monomer, p22HBP localizes to cytoplasm and contains a 21 amino acid chemoattractant within its N-terminus that functions as a natural ligand for FPR3. p22HBP is a member of the HEBP family and binds N-methylprotoporphyrin and metalloporphyrins with similar affinity to porphyrinogens. The gene encoding p22HBP maps to human chromosome 12, which encodes over 1,100 genes and comprises approximately 4.5% of the human genome. Chromosome 12 is associated with a variety of diseases and afflictions, including hypochondrogenesis, achondrogenesis, Kniest dysplasia, Noonan syndrome and trisomy 12p, which causes facial developmental defects and seizure disorders.