major basic protein major basic protein eosinophil major basic protein, often shortened to major basic protein (mbp; also called proteoglycan 2 (prg2)) is encoded in humans by the prg2 gene. prg2available structurespdbortholog search: pdbe rcsb list of pdb id codes1h8u, 2brs, 4qxxidentifiersaliasesprg2, bmpg, mbp, mbp1, proteoglycan 2, bone marrow (natural killer cell activator, eosinophil granule major basic protein), prombp, proteoglycan 2, pro eosinophil major basic proteinexternal idsomim: 605601 mgi: 103294 homologene: 2044 genecards: prg2 gene location (human)chr.chromosome 11 (human)band11q12.1start57,386,780 bpend57,390,650 bpgene location (mouse)chr.chromosome 2 (mouse)band2 d|2 49.45 cmstart84,810,805 bpend84,813,976 bprna expression patternbgeehumanmouse (ortholog)top expressed inplacentabone marrowbone marrow cellsright lobe of liversubcutaneous adipose tissuespleenskin of abdomenmonocytebloodright lungtop expressed inbone marrowankle jointspleenfemurbody of femurthymusduodenumcochleajejunumbelly cordmore reference expression databiogpsmore reference expression datagene ontologymolecular function heparin binding carbohydrate binding extracellular matrix structural constituent conferring compression resistance cellular component extracellular region transport vesicle cytoplasmic vesicle extracellular exosome ficolin-1-rich granule lumen collagen-containing extracellular matrix biological process defense response to bacterium immune system process defense response to nematode negative regulation of interleukin-10 production positive regulation of interleukin-4 production immune response neutrophil degranulation sources:amigo / quickgoorthologsspecieshumanmouseentrez555319074ensemblensg00000186652ensmusg00000027073uniprotp13727q61878refseq (mrna)nm_002728nm_001243245nm_001302926nm_001302927nm_008920refseq (protein)np_001230174np_001289855np_001289856np_002719np_032946location (ucsc)chr 11: 57.39 – 57.39 mbchr 2: 84.81 – 84.81 mbpubmed searchwikidataview/edit humanview/edit mouse function the protein encoded by this gene is the predominant constituent of the crystalline core of the eosinophil granule. high levels of the proform of this protein are also present in placenta and pregnancy serum, where it exists as a complex with several other proteins including pregnancy-associated plasma protein a (pappa), angiotensinogen (agt), and c3dg. this protein may be involved in antiparasitic defense mechanisms as a cytotoxin and helmintho-toxin, and in immune hypersensitivity reactions. it is directly implicated in epithelial cell damage, exfoliation, and bronchospasm in allergic diseases. prg2 is a 117-residue protein that predominates in eosinophil granules. it is a potent enzyme against helminths and is toxic towards bacteria and mammalian cells in vitro. the eosinophil major basic protein also causes the release of histamine from mast cells and basophils, and activates neutrophils and alveolar macrophages. structure structurally the major basic protein (mbp) is similar to lectins (sugar-binding proteins), and has a fold similar to that seen in c-type lectins. however, unlike other c-type lectins (those that bind various carbohydrates in the presence of calcium), mbp does not bind either calcium or any of the other carbohydrates that this family recognize. instead, mbp recognises heparan sulfate proteoglycans. two crystallographic structures of mbp have been determined. interactions major basic protein has been shown to interact with pregnancy-associated plasma protein a.