title: cDNA cloning and primary structure analysis of C1qR(P), the human C1q/MBL/SPA receptor that mediates enhanced phagocytosis in vitro.
abstract: The complement protein C1q, mannose-binding lectin (MBL), and pulmonary surfactant protein A (SPA) are structurally similar molecules that enhance phagocytic function in vitro. Monoclonal antibodies R3 and R139, which inhibit the enhancement triggered by these three ligands, were used to purify a 126,000 M(r) cell surface protein designated C1qR(P). Amino acid sequence was obtained and the corresponding cDNA was cloned. C1qR(P) is a novel type I membrane protein with the following putative structural elements: a C-type carbohydrate recognition domain, five EGF-like domains, a transmembrane domain, and a short cytoplasmic tail. All peptides identified by amino acid sequencing are encoded by the cDNA. Additionally, an anti-peptide antiserum was generated, which is reactive with C1qR(P). The data indicate that the cloned cDNA encodes the receptor that plays a role in C1q/MBL/SPA-mediated removal or destruction of pathogens and immune complexes by phagocytosis.
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine 92697, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: Nepomuceno
authors.forename: A H
authors.initials: AH
authors.lastname: Henschen-Edman
authors.forename: W H
authors.initials: WH
authors.lastname: Burgess
authors.forename: A J
authors.initials: AJ
authors.lastname: Tenner
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D003001:Cloning, Molecular; D037222:Collectins; D003166:Complement Activating Enzymes / Q000032:analysis / Q000378:metabolism / Q000502:physiology; D018076:DNA, Complementary / Q000032:analysis*; D006801:Humans; D018960:Hyaluronan Receptors; D016403:Lymphoma, Large B-Cell, Diffuse; D008262:Macrophage Activation / Q000502:physiology; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D008969:Molecular Sequence Data; D010587:Phagocytosis / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000378:metabolism*; D011951:Receptors, Complement / Q000032:analysis* / Q000378:metabolism* / Q000502:physiology; D011971:Receptors, Immunologic / Q000032:analysis* / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: C087299:C1QBP protein, human; D002352:Carrier Proteins; D037222:Collectins; D018076:DNA, Complementary; D018960:Hyaluronan Receptors; D008562:Membrane Glycoproteins; D024101:Mitochondrial Proteins; D011663:Pulmonary Surfactants; D011951:Receptors, Complement; D011971:Receptors, Immunologic; C032402:complement 1q receptor; D003166:Complement Activating Enzymes