Cytotoxin and helminthotoxin. Also induces non-cytolytic histamine release from human basophils. Involved in antiparasitic defense mechanisms and immune hypersensitivity reactions. The proform acts as a proteinase inhibitor, reducing the activity of PAPPA.
Specificity
Natural and recombinant Human Bone marrow proteoglycan
Subcellular Location
Eosinophil granule major basic protein Cytoplasmic vesicle secretory vesicle The proform is secreted. The mature protein is found in the matrix of the eosinophil's large specific granule.
In pregnancy serum, the proform exists as a disulfide-linked 2:2 heterotetramer with PAPPA, as a disulfide-linked 2:2 heterotetramer with AGT, and as a complex (probably a 2:2:2 heterohexamer) with AGT and C3dg.