A protein called macrophage migration inhibitory factor (MIF) [1] seems to exerts an important role in host inflammatory responses. It play a pivotal role in the host response to endotoxic shock and appears to serve as a pituitary "stress" hormone that regulates systemic inflammatory responses. MIF is a secreted protein of 115 residues which is not processed from a larger precursor.

D-dopachrome tautomerase [2] is a mammalian cytoplasmic enzyme involved in melanin biosynthesis and that tautomerizes D-dopachrome with concomitant decarboxylation to give 5,6-dihydroxyindole (DHI). It is a protein of 117 residues highly related to MIF.

It must be noted that MIF binds glutathione and has been said to be related to glutathione S-transferases. This assertion has been later disproved [3].

As a signature pattern for these proteins, we selected a conserved region located in the central section.