cDNA cloning and primary structure analysis of C1qR(P), the human C1q/MBL/SPA receptor that mediates enhanced phagocytosis in vitro

Immunity. 1997 Feb;6(2):119-29. doi: 10.1016/s1074-7613(00)80419-7.


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

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Carrier Proteins / metabolism*
  • Cloning, Molecular
  • Collectins
  • Complement Activating Enzymes / analysis
  • Complement Activating Enzymes / metabolism
  • Complement Activating Enzymes / physiology
  • DNA, Complementary / analysis*
  • Humans
  • Hyaluronan Receptors*
  • Lymphoma, Large B-Cell, Diffuse
  • Macrophage Activation / physiology
  • Membrane Glycoproteins*
  • Mitochondrial Proteins
  • Molecular Sequence Data
  • Phagocytosis / physiology*
  • Pulmonary Surfactants / metabolism*
  • Receptors, Complement / analysis*
  • Receptors, Complement / metabolism*
  • Receptors, Complement / physiology
  • Receptors, Immunologic / analysis*
  • Receptors, Immunologic / metabolism*
  • Tumor Cells, Cultured


  • C1QBP protein, human
  • Carrier Proteins
  • Collectins
  • DNA, Complementary
  • Hyaluronan Receptors
  • Membrane Glycoproteins
  • Mitochondrial Proteins
  • Pulmonary Surfactants
  • Receptors, Complement
  • Receptors, Immunologic
  • complement 1q receptor
  • Complement Activating Enzymes

Associated data

  • GENBANK/U94333