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.
Publication types
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Base Sequence
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Carrier Proteins / metabolism*
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Cloning, Molecular
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Collectins
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Complement Activating Enzymes / analysis
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Complement Activating Enzymes / metabolism
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Complement Activating Enzymes / physiology
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DNA, Complementary / analysis*
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Humans
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Hyaluronan Receptors*
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Lymphoma, Large B-Cell, Diffuse
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Macrophage Activation / physiology
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Membrane Glycoproteins*
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Mitochondrial Proteins
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Molecular Sequence Data
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Phagocytosis / physiology*
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Pulmonary Surfactants / metabolism*
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Receptors, Complement / analysis*
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Receptors, Complement / metabolism*
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Receptors, Complement / physiology
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Receptors, Immunologic / analysis*
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Receptors, Immunologic / metabolism*
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Tumor Cells, Cultured
Substances
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C1QBP protein, human
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Carrier Proteins
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Collectins
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DNA, Complementary
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Hyaluronan Receptors
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Membrane Glycoproteins
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Mitochondrial Proteins
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Pulmonary Surfactants
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Receptors, Complement
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Receptors, Immunologic
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complement 1q receptor
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Complement Activating Enzymes