title: Identification of human CD93 as the phagocytic C1q receptor (C1qRp) by expression cloning.
abstract: CD93 is a approximately 120 kDa O-sialoglycoprotein that within the hematopoietic system is selectively expressed on cells of the myeloid lineage. So far, its primary structure and function were unknown. We used retroviral-expression cloning to isolate the CD93 cDNA. Sequence analysis revealed that CD93 is identical to a protein on human phagocytes termed C1q receptor (C1qRp). C1qRp was shown previously to mediate enhancement of phagocytosis in monocytes and was suggested to be a receptor of C1q and two other structurally related molecules. When studying CD93 transductants and control cells, we found that cells expressing CD93 have enhanced capacity to bind C1q. Furthermore, we show that immature dendritic cells (DC) express CD93/C1qRp, and mature DC, known to have reduced capacity for antigen uptake and to have lost the ability to phagocytose, show weak-to-negative CD93/C1qRp expression.
authors.affiliation: Institute of Immunology, University of Vienna, A-1090 Vienna, Austria. peter.steinberger@univie.ac.at
authors.forename: Peter
authors.initials: P
authors.lastname: Steinberger
authors.forename: Andreas
authors.initials: A
authors.lastname: Szekeres
authors.forename: Stefan
authors.initials: S
authors.lastname: Wille
authors.forename: Johannes
authors.initials: J
authors.lastname: Stöckl
authors.forename: Nicole
authors.initials: N
authors.lastname: Selenko
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Prager
authors.forename: Günther
authors.initials: G
authors.lastname: Staffler
authors.forename: Otto
authors.initials: O
authors.lastname: Madic
authors.forename: Hannes
authors.initials: H
authors.lastname: Stockinger
authors.forename: Walter
authors.initials: W
authors.lastname: Knapp
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology*; D001483:Base Sequence; D002352:Carrier Proteins; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D003713:Dendritic Cells / Q000276:immunology*; D006801:Humans; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins / Q000235:genetics / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D010586:Phagocytes / Q000276:immunology*; D010587:Phagocytosis; D011951:Receptors, Complement / Q000235:genetics* / Q000276:immunology*; D012795:Sialoglycoproteins / Q000235:genetics* / Q000276:immunology*; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; C087299:C1QBP protein, human; C490193:C1qbp protein, mouse; D002352:Carrier Proteins; D018076:DNA, Complementary; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011951:Receptors, Complement; D012795:Sialoglycoproteins; C032402:complement 1q receptor