Matriptase-2 is a cell surface serine protease with a modular structure. The exploration of its function in iron homeostasis was
of significance for the understanding of the regulation of hepcidin expression, the master protein in iron control. Mutations in matriptase-
2 cause iron-refractory iron deficiency anemia (IRIDA), an iron deficiency disorder where the level of hepcidin is inappropriately high.
Matriptase-2 controls hepcidin expression through the suppression of bone morphogenetic protein (BMP)/sons of mothers against decapentaplegic
homologue protein (SMAD) signaling, probably by cleaving the BMP co-receptor hemojuvelin. Since prospective studies revealed
that genetic inactivation of matriptase-2 reduces iron loading in different mouse models, matriptase-2 becomes highly attractive as
a novel target for the design of low-molecular weight inhibitors. The first synthetic peptidomimetic matriptase-2 inhibitors have been reported.
A computational model of the active site of matriptase-2 based on the X-ray crystal structure of the close homologue matriptase
was generated and mutational studies were performed in order to identify critical amino acids specifying the preferred recognition site of
matriptase-2. So far, the only known putative natural substrates of matriptase-2 are hemojuvelin and matriptase-2 itself, as this protease
undergoes complex auto-processing during zymogen activation. Cleavage sites within both natural substrates were identified.
Keywords: Active site, cleavage site, hepcidin, iron homeostasis, matriptase, matriptase-2, type II transmembrane serine protease.
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