Purification and partial characterization of acrosome reaction inhibiting glycoprotein from human seminal plasma
The human acrosome reaction (AR; sperm exocytosis) is absolutely required for fertilization. In the course of further characterizing the AR and its control, an AR-inhibiting glycoprotein (ARIG) from human seminal plasma was purified by differential centrifugation, carboxymethyl cellulose chromatogra...
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Veröffentlicht in: | Biology of reproduction 1995-07, Vol.53 (1), p.201-208 |
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Zusammenfassung: | The human acrosome reaction (AR; sperm exocytosis) is absolutely required for fertilization. In the course of further characterizing
the AR and its control, an AR-inhibiting glycoprotein (ARIG) from human seminal plasma was purified by differential centrifugation,
carboxymethyl cellulose chromatography, chromatofocusing, and Sephacryl S300 gel filtration. A highly purified protein with
a molecular weight of 74,000 was obtained as determined by gel filtration and SDS-PAGE. ARIG eluted in a narrow pH range (6.2-5.4)
during chromatofocusing, corresponding to a pl of 5.8 +/- 0.4. It had covalent modifications, including internal disulfide
bonds, and both complex N-linked and O-linked oligosaccharide chains. Lectin analysis suggested that sialic acid was absent
and that the complex oligosaccharide chains had sequences containing galactose, galactosamine, and/or glucosamine in a beta
1-4 linkage. Mannose residues were also present. When ARIG was added to in vitro-capacitated human spermatozoa 30 min prior
to the calcium ionophore A23187, the AR was significantly inhibited (ID50 = 8.5 micrograms/ml). In addition, ARIG reduced
sperm exocytosis in response to atrial natriuretic peptide (a guanylate cyclase activator) and to the protein kinase C activators
phorbol myristate acetate and dioctanoylglycerol. The ability of ARIG to block the human AR induced by a variety of agonists
and the fact that biological activity of the protein was lost after removal of its sugar moieties suggests that it may function
as a general inhibitor of sperm exocytosis and that its interaction with spermatozoa may be mediated by carbohydrate-binding
proteins on the sperm cell. |
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ISSN: | 0006-3363 1529-7268 |
DOI: | 10.1095/biolreprod53.1.201 |