Abstract
A novel murine plasma membrane protein has been identified in subpopulations of macrophages. It has an intracellular N-terminal domain, a transmembrane domain, and an extracellular region with a short spacer, an 89 Gly-Xaa-Yaa repeat-containing collagenous domain, and a C-terminal cysteine-rich domain. In situ hybridization and immunohistochemical staining have localized the protein to a subset of macrophages in the marginal zone of the spleen and the medullary cord of lymph nodes. No expression was observed in macrophages of liver or lung. Transfected COS cells synthesized a native trimeric plasma membrane protein that bound labeled bacteria and acetylated LDL, but not yeast or Ficoll. The results suggest that the novel protein is a macrophage-specific membrane receptor with a role in host defense, as it shows postnatal expression in macrophages, which are considered responsible for the binding of bacterial antigens and phagocytosis.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Animals
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Carrier Proteins / biosynthesis
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Carrier Proteins / genetics*
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DNA, Complementary / genetics
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Escherichia coli / metabolism*
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Fluorescent Antibody Technique
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In Situ Hybridization
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Lipoproteins, LDL / metabolism
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Lymphoid Tissue / chemistry*
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Macrophages / chemistry*
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Membrane Proteins / biosynthesis
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Membrane Proteins / genetics*
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Mice
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Molecular Sequence Data
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Protein Binding
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Protein Conformation
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RNA, Messenger / analysis
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Receptors, Immunologic / genetics
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Receptors, Lipoprotein*
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Receptors, Scavenger
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Recombinant Proteins / biosynthesis
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Scavenger Receptors, Class B
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Sequence Analysis, DNA
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Tissue Distribution
Substances
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Carrier Proteins
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DNA, Complementary
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Lipoproteins, LDL
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Marco protein, mouse
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Membrane Proteins
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RNA, Messenger
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Receptors, Immunologic
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Receptors, Lipoprotein
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Receptors, Scavenger
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Recombinant Proteins
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Scarb1 protein, mouse
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Scavenger Receptors, Class B
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acetyl-LDL