Biosynthesis of properdin
Properdin (P) is synthesized by the human promyelocytic cell line, HL-60, after differentiation with DMSO. The secreted P was physiochemically indistinguishable from purified plasma P. It was polymerized and able to bind to C3IBb-Sepharose but not to C3i-Sepharose. No extracellular precursor was pre...
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Veröffentlicht in: | The Journal of immunology (1950) 1989-02, Vol.142 (3), p.842-847 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Properdin (P) is synthesized by the human promyelocytic cell line, HL-60, after differentiation with DMSO. The secreted P was physiochemically indistinguishable from purified plasma P. It was polymerized and able to bind to C3IBb-Sepharose but not to C3i-Sepharose. No extracellular precursor was present. The intracellular form, detected between 1 and 4 h after labeling, was similar but had a slightly lower Mr. It also bound reversibly to C3iBb-Sepharose, and polymers could be demonstrated by cross-linking. Pulse-chase experiments suggested the existence of an earlier, but undetectable, intracellular precursor(s). This form could not be immunoprecipitated even when harsh solubilization conditions and/or antibodies against reduced and denatured P were utilized. Studies with endoglycosidases F and H and tunicamycin indicated that the detectable intracellular precursor contains high mannose N-linked carbohydrate that is processed to the complex form before secretion. The sugars are not required for polymerization, secretion, or functional activity, or responsible for the electrophoretic heterogeneity. Polymerization of P is therefore an early intracellular event, perhaps carefully controlled to prevent anomalous aggregation. |
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ISSN: | 0022-1767 1550-6606 |
DOI: | 10.4049/jimmunol.142.3.842 |