Identification of GRASP-1 as a novel 97 kDa autoantigen localized to endosomes

Clin Immunol. 2005 Aug;116(2):108-17. doi: 10.1016/j.clim.2005.03.021.


We have identified an autoantigen that is recognized by antibodies from an 18-year-old female with a history of recurrent infections who later in her clinical course developed Raynaud's phenomenon and telangiectasias. By indirect immunofluorescence (IIF), the index serum produced a unique cytoplasmic discrete speckled (CDS) staining pattern that partially colocalized with early endosome antigen 1 (EEA1) but not Golgi complex or other cytoplasmic organelles in HEp-2 cells. When HEp-2 cells were treated with 0.1 N HCl, the cytoplasmic speckled staining of the index serum was markedly decreased, suggesting that the reactive antigen was soluble. Western blot analysis showed a reactive approximately 97 kDa protein in a saline soluble protein preparation from HeLa cells. Mass spectrometric analysis of the excised 97 kDa band that was immunoprecipitated from HeLa cell extracts identified GRASP-1 as a possible target. The index serum and anti-GRASP-1 antibodies colocalized to structures in the cytoplasm of HEp-2 cells. Synthetic peptides representing the full-length GRASP-1 protein were used to identify reactive epitopes. Like many other cytoplasmic autoantigens, GRASP-1 has numerous coiled-coil domains throughout the protein with the exception of short segments at the amino and carboxyl terminus.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Amino Acid Sequence
  • Antibody Specificity / immunology
  • Autoantigens / immunology*
  • Autoantigens / metabolism
  • Blotting, Western
  • Carrier Proteins / genetics
  • Carrier Proteins / immunology*
  • Cell Line, Tumor
  • Endosomes / immunology
  • Endosomes / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Epitope Mapping
  • Epitopes / genetics
  • Epitopes / immunology
  • Female
  • Fluorescent Antibody Technique, Indirect
  • HSP110 Heat-Shock Proteins
  • HeLa Cells
  • Heat-Shock Proteins / immunology
  • Humans
  • Hydrochloric Acid / chemistry
  • Immunoprecipitation
  • Infections / blood
  • Infections / immunology
  • Infections / pathology
  • Mass Spectrometry
  • Membrane Proteins / immunology
  • Molecular Sequence Data
  • Peptide Fragments / immunology
  • Raynaud Disease / blood
  • Raynaud Disease / immunology
  • Raynaud Disease / pathology
  • Recurrence
  • Sequence Homology, Amino Acid
  • Telangiectasis / blood
  • Telangiectasis / immunology
  • Telangiectasis / pathology
  • Vesicular Transport Proteins


  • Autoantigens
  • Carrier Proteins
  • Epitopes
  • GRIPAP1 protein, human
  • HSP110 Heat-Shock Proteins
  • HSPA4 protein, human
  • Heat-Shock Proteins
  • Membrane Proteins
  • Peptide Fragments
  • Vesicular Transport Proteins
  • early endosome antigen 1
  • Hydrochloric Acid