Titre
Molecular structure and functional characterization of a human complement cytolysis inhibitor found in blood and seminal plasma: identity to sulfated glycoprotein 2, a constituent of rat testis fluid
Type
article
Institution
UNIL/CHUV/Unisanté + institutions partenaires
Auteur(s)
Jenne, D. E.
Auteure/Auteur
Tschopp, J.
Auteure/Auteur
Liens vers les personnes
Liens vers les unités
ISSN
0027-8424
Statut éditorial
Publié
Date de publication
1989-09
Volume
86
Numéro
18
Première page
7123
Dernière page/numéro d’article
7
Notes
Journal Article --- Old month value: Sep
Résumé
A component of soluble terminal complement complexes was identified and affinity-purified to homogeneity by using a monoclonal antibody previously developed against the soluble C5b-9 complex. The protein, which we have designated complement cytolysis inhibitor (CLI), has a molecular mass of 70 kDa and consists of two nonidentical, disulfide-linked subunits of 35 kDa. Partial amino acid sequences determined for the amino-termini of the two subunits were identical with those of a recently characterized serum protein called SP-40,40. An almost full-length cDNA clone of 1651 base pairs was isolated from a human liver cDNA library by using long synthetic oligonucleotides as probes. The encoded amino acid sequence of CLI consists of 427 amino acid residues preceded by a 21-residue-long typical signal peptide and shows an overall 75.6% amino acid sequence homology to sulfated glycoprotein 2 (SGP-2), a major Sertoli cell-derived protein of rat testis fluid. As in SGP-2, proteolytic processing between residues 206 and 207 yields the two disulfide-linked subunits of plasma CLI. CLI and SGP-2 were shown to be orthologous single-copy genes in humans and rats by Southern blotting experiments. In addition, CLI was immunologically identified in human seminal plasma. Functional studies with purified terminal complement components showed that CLI suppresses the cytolytic potential of nascent C5b-7 complexes at physiological blood plasma concentrations (approximately 50 micrograms/ml). Its presence on the surface of mature sperm cells and its relative abundance in seminal plasma (approximately 250 micrograms/ml) suggest that CLI protects sperm cells and epithelial tissues against complement attack in the male reproductive tract.
Sujets
PID Serval
serval:BIB_A1B907A042B5
PMID
Open Access
Oui
Date de création
2008-01-24T14:18:54.616Z
Date de création dans IRIS
2025-05-21T02:50:38Z