Introduction of mannose binding protein-type phosphatidylinositol recognition into pulmonary surfactant protein A

Biochemistry. 1999 Jun 1;38(22):7321-31. doi: 10.1021/bi990353e.


Pulmonary surfactant protein A (SP-A) and mannose-binding protein A (MBP-A) are collectins in the C-type lectin superfamily. These collectins exhibit unique lipid binding properties. SP-A binds to dipalmitoyl phosphatidylcholine (DPPC) and galactosylceramide (GalCer) and MBP-A binds to phosphatidylinositol (PI). SP-A also interacts with alveolar type II cells. Monoclonal antibodies (mAbs PE10 and PC6) that recognize human SP-A inhibit the interactions of SP-A with lipids and alveolar type II cells. We mapped the epitopes for anti-human SP-A mAbs by a phage display peptide library. Phage selected by mAbs displayed the consensus peptide sequences that are nearly identical to 184TPVNYTNWYRG194 of human SP-A. The synthetic peptide GTPVNYTNWYRG completely blocked the binding of mAbs to human SP-A. Chimeric proteins were generated in which the rat SP-A region Thr174-Gly194 or the human SP-A region Ser174-Gly194 was replaced with the MBP-A region Thr164-Asp184 (rat ama4 or hu ama4, respectively). The mAbs failed to bind hu ama4. Rat ama4 bound to an affinity matrix on mannose-sepharose but lost all of the SP-A functions except carbohydrate binding and Ca2+-independent GalCer binding. Strikingly, the rat ama4 chimera acquired the PI binding property that MBP-A exhibits. This study demonstrates that the amino acid residues 174-194 of SP-A and the corresponding region of MBP-A are critical for SP-A-type II cell interaction and Ca2+-dependent lipid binding of collectins.

Publication types

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

MeSH terms

  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Binding Sites, Antibody / drug effects
  • Binding, Competitive
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Epitopes / immunology
  • Humans
  • Male
  • Mannose / metabolism*
  • Mannose-Binding Lectins
  • Phosphatidylinositols / antagonists & inhibitors
  • Phosphatidylinositols / metabolism*
  • Proteolipids / antagonists & inhibitors
  • Proteolipids / genetics
  • Proteolipids / immunology
  • Proteolipids / metabolism*
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / drug effects
  • Pulmonary Alveoli / metabolism
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants / antagonists & inhibitors
  • Pulmonary Surfactants / genetics
  • Pulmonary Surfactants / immunology
  • Pulmonary Surfactants / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Fusion Proteins / pharmacology


  • Antibodies, Monoclonal
  • Carrier Proteins
  • Epitopes
  • Mannose-Binding Lectins
  • Phosphatidylinositols
  • Proteolipids
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants
  • Recombinant Fusion Proteins
  • Mannose