Lipocortin 1 co-associates with cytokeratins 8 and 18 in A549 cells via the N-terminal domain

Biochim Biophys Acta. 1998 Jan 2;1401(1):39-51. doi: 10.1016/s0167-4889(97)00120-1.


An affinity chromatography strategy was used to search for proteins in A549 cells which interact with the N-terminus of lipocortin 1 (annexin 1). Using the biologically active fragment Lc13-25 as the affinity ligand, two proteins of molecular weight (m.w.) 52 and 48kDa were extracted. Affinity blots of these proteins bound iodinated Lc13-25. Partial tryptic digests of these proteins were analysed by matrix assisted laser desorption mass spectrometry and found to display fragmentation patterns with a strong similarity to those of cytokeratin 8 and 18 respectively. Subsequent blotting with a panel of specific cytokeratin antibodies strongly supported the idea that the two proteins were cytokeratin 8 and cytokeratin 18. Cytokeratin 8 was isolated from A549 cells in intermediate filament (IF) preparations which were also found to contain lipocortin 1 as a potential intermediate filament associated protein (IFAP). This association persisted throughout cycles of IF assembly and disassembly. Dual-labelling immuno-histochemistry in A549 cells showed strong co-localization of lipocortin 1 and cytokeratin 8. The implications of this finding are discussed in the light of the biological activity and possible function of lipocortin 1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Annexin A1 / analysis
  • Annexin A1 / metabolism*
  • Cell Line
  • Chromatography, Affinity / methods
  • Humans
  • Intermediate Filaments / chemistry*
  • Keratins / analysis
  • Keratins / chemistry
  • Keratins / metabolism*
  • Molecular Weight
  • Peptide Fragments / analysis
  • Peptide Fragments / chemistry
  • Protein Binding
  • Sequence Analysis


  • Annexin A1
  • Peptide Fragments
  • Keratins