Description
MIF (or macrophage migration inhibitory factor) was the first lymphokine/cytokine to be recognized in the pregenomics era . Regardless, it is one of the least understood of all inflammatory mediators . Secretion occurs nonclassically via an ABCA1 transporter. The molecule consists of two alpha -helices and six beta -strands, four of which form a beta -sheet. The two remaining beta -strands interact with other MIF molecules, creating a trimer . Structure-function studies suggest MIF is bifunctional with segregated topology. The N- and C-termini mediate enzyme activity (in theory). Phenylpyruvate tautomerase activity (enol-to-keto) has been demonstrated and is dependent upon Pro at position #1. Amino acids 50 – 65 have also been suggested to contain thiol-protein oxidoreductase activity.