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PRG3 encodes major basic protein 2 (MBP2), a C-type lectin-like fold cationic granule effector with no enzymatic activity, classifying it as a non-enzymatic effector protein.
"PRG3 encodes major basic protein 2 (MBP2), a member of the MBP family of eosinophil granule proteins that adopt a C-type lectin-like fold (lectin-like structural homology rather than canonical Ca2+-dependent lectin activity). The MBP family is best understood as cationic secretory/granule effector proteins that can damage membranes and stimulate immune and stromal cells; no enzymatic reaction has been assigned to MBP family proteins (including MBP1 and MBP2)."
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PRG3/MBP2 is localized to the eosinophil secondary (specific) granule, not tertiary granules.
"PRG3/MBP2 is localized to the eosinophil secondary (specific) granule, supported by biochemical identification in granule lysates and immunologic localization assays discussed in the foundational characterization/review."
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PRG3/MBP2 has lower predicted pI (~8.7) than MBP1 (~11.4) and is generally less potent biologically, consistent with reduced cationicity as a determinant of effector strength.
"Foundational synthesis reports MBP2 has lower predicted pI (~8.7) than MBP1 (~11.4) and is generally less potent in biological activities, consistent with reduced cationicity as a determinant of effector strength."
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MBPH/PRG3 grouped with MBP family proteins capable of membrane disintegration and antimicrobial activity; depletion linked to impaired Candida albicans killing.
"MBPH/PRG3 is grouped with MBP family proteins described as capable of membrane disintegration and antimicrobial activity, and changes in phagosomal granule content (including MBPH/PRG3 and MBP) are linked to impaired Candida albicans yeast killing in mobilized granulocytes."
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PRG3 ranks among the top 15 most abundant proteins in human peripheral blood eosinophils, supporting it as a prominent eosinophil granule constituent.
"Deep proteomics placed PRG3 (bone marrow proteoglycan 3 / MBP2) among the major eosinophil granule proteins and among the top 15 most abundant eosinophil proteins, supporting its status as a prominent eosinophil granule constituent and useful marker of eosinophil content/degranulation."