Epitope mapping for monoclonal antibody against human surfactant protein A (SP-A) that alters receptor binding of SP-A and the SP-A-dependent regulation of phospholipid secretion by alveolar type II cells

Biochim Biophys Acta. 1995 Aug 3;1257(3):214-22. doi: 10.1016/0005-2760(95)00068-n.


Surfactant protein A (SP-A) is a lung-specific glycoprotein in pulmonary surfactant and has a collagen like sequence on its N-terminal. SP-A has been shown to function as an inhibitor of phospholipid secretion by primary culture of alveolar type II cells via cell surface receptor(s) for SP-A. In a previous report, we showed that the C-terminal non-collagen like domain of human SP-A possessed the biological activities, and that a monoclonal antibody against human SP-A, PE10, abolished the biological activity of SP-A (Murata et al. (1993) Biochem. J. 291, 71-76). In the present study, we investigated an epitope of SP-A for PE10. Western blot analysis with fragmented peptides of human SP-A generated by both lysyl endopeptidase and BrCN showed that PE10 reacted with the peptide corresponding with Glu202 to the C-terminal but that it lacked the ability to bind to the peptide corresponding with Tyr208 to the C-terminal. The antibodies against a synthetic peptide (P1) corresponding with Glu202 to Asn217 of human SP-A inhibited the binding of PE10 to SP-A, suggesting that a similar site was recognized by both PE10 and anti-P1 antibodies. Anti-P1 antibodies as well as PE10 suppressed the biological activity of SP-A. A direct interaction between P1 and rat lung membranes, or between P1 and alveolar type II cell membranes was shown from the measurement of the fluorescence emission spectra of dansyl-labeled P1. These results suggest that an area contiguous to or near the region from Glu202 to Met207 of SP-A is important for expressing the biological activities.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal / immunology
  • Binding, Competitive
  • Blotting, Western
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Dansyl Compounds
  • Epitope Mapping*
  • Glycoproteins / chemistry*
  • Glycoproteins / immunology
  • Glycoproteins / metabolism
  • Humans
  • Lung / metabolism
  • Molecular Sequence Data
  • Peptide Fragments / chemistry
  • Peptide Fragments / immunology
  • Peptide Fragments / metabolism
  • Phosphatidylcholines / antagonists & inhibitors
  • Phosphatidylcholines / metabolism*
  • Proteolipids / chemistry*
  • Proteolipids / immunology
  • Proteolipids / pharmacology
  • Proteolipids / physiology
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / metabolism*
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants / chemistry*
  • Pulmonary Surfactants / immunology
  • Pulmonary Surfactants / pharmacology
  • Pulmonary Surfactants / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Serine Endopeptidases / metabolism
  • Spectrometry, Fluorescence


  • Antibodies, Monoclonal
  • Dansyl Compounds
  • Glycoproteins
  • Peptide Fragments
  • Phosphatidylcholines
  • Proteolipids
  • Pulmonary Surfactant-Associated Protein A
  • Pulmonary Surfactant-Associated Proteins
  • Pulmonary Surfactants
  • Serine Endopeptidases
  • lysyl endopeptidase