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  • 1
    Electronic Resource
    Electronic Resource
    Characterization of a cDNA clone coding for human testis membrane cofactor protein (MCP, CD46) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 34 (1993), S. 107-113 
    Details
    ISSN: 1040-452X
    Keywords: Complement regulatory protein ; Spermatozoa ; Fertilization ; Gene structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Membrane cofactor protein (MCP) is a complement regulatory protein that acts as a cofactor for the cleavage of C3b and C4b by the serine protease factor I. We have previously reported the characterization of a functional MCP molecule on the acrosomal membrane. This protein migrated as a single band with a molecular weight of 40,000 Da, which is 10,000-20,000 Da smaller than the known MCP molecules, and is devoid of N-and O-linked sugars. We have proposed that the difference in molecular weight resulted from the lack of sugars. To investigate if this is due to the absence of glycosylation sites, we have characterized a cDNA clone from a human testis cDNA library. This cDNA corresponds to a peculiar MCP form previously described, which is characterized by the presence of the serine/threonine/proline-rich exon C (STPC) and the cytoplasmic tail known as CYT2, and we conclude that the absence of mature oligosaccharide of the sperm MCP cannot be totally attributed to a defect of N- and O-glycosylation sequences but rather reflects an alteration of the mechanisms of glycosylation in spermatozoa. The presence of functional MCP on the acrosomal membrane, as well as the other complement regulatory protein, decay-accelerating factor, strongly suggests that these proteins may act concomitantly to protect the acrosome-reacted spermatozoa from the attack of the complement present in the female genital tract. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080340117
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of the complement regulatory protein CD59 on human spermatozoa: Characterization and role in gametic interaction (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 38 (1994), S. 338-346 
    Details
    ISSN: 1040-452X
    Keywords: Human sperm antigens ; Complement regulatory proteins ; Protectin CD59 ; Membrane attack complex ; Cell-to-cell adhesion ; Gametic interaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: Protectin (CD59) is a complement regulatory protein which blocks the membrane attack complex during complement activation. CD59 was identifield on the human sperm surface by means of H19, an IgG1 anti-protectin mouse monoclonal antibody. Using Indirect immunofluorescence, flow cytometry and immunoperoxidase, CD59 was found to be present on the whole plasma membrane including the head and tail of fresh ejaculated, capacitated and acrosome-reacted spermatozoa. Immunoperoxidase staining of normal testicular sections indicated that this protein was already present on intraluminal germ cells. Analysis of this sperm protein by gel electrophoresis and immunoblotting revealed that its molecular weight of 20 kDa was comparable to that of CD59 expressed on peripheral blood cells (erythrocytes, lymphocytes) and that it was bound to the membrane through a glycophospholipid tail which could be released after treatment with phosphatidylinositol-specific phospholipase C. Associated to membrane cofactor protein (CD46) and decay accelerating factor (CD55) located in the acrosomal membranes, CD59 may participate to the protection of male gametes against complement-mediated damage as they travel through the female genital tract. Moreover CD59, known as an adhesion molecule involved in lymphocyte rosettes, may also participate in cell to cell adhesion during gametic interaction since H19 inhibited sperm binding and reduced the penetration rate and index during the hamster egg penetration test. © 1994 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080380316
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  • 3
    Electronic Resource
    Electronic Resource
    Localization and characterization of the acrosomal antigen recognized by GB24 on human spermatozoa (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 27 (1990), S. 173-178 
    Details
    ISSN: 1040-452X
    Keywords: Human sperm antigen ; Monoclonal antibody ; Trophoblast-leukocyte cross-reaction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: GB24, a mouse monoclonal antibody, recognizes a trophoblast-leukocyte cross-reactive antigen (TLX), which is likely identical to the membrane cofactor protein (MCP), a complement regulatory protein. GB24 reacts also with a human acrosomal sperm antigen (Fénichel et al.: J Reprod Fertil 87:699-706, 1989). By immunofluorescence or immunoperoxidase, testicular, epididymal, and ejaculated spermatozoa were found to be positive after fixation by acetone. Motile, suspended spermatozoa became positive only through conditions known to induce acrosome reaction (A23187, follicular fluid, contact with oocytes). Ultrastructural studies with immunogold staining localized this protein on the inner acrosome membrane and in the acrosomal content. By SDS-polyacrylamide gel electrophoresis, GB24 immunoprecipitated a unique protein of 48 kDa from capacitated and A23187-induced spermatozoa under reducing conditions. No cross-reactivity was found with mouse, boar, or ram spermatozoa. Localization of this human sperm antigen recognized by GB24 and its similarity with the TLX-MCP family antigens would suggest a possible role of this molecule during fertilization in sperm-egg binding or immune protection.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrd.1080270214
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