Cell surface expression of the 70-kD component of Ku, a DNA-binding nuclear autoantigen.
AUTOR(ES)
Prabhakar, B S
RESUMO
The Ku complex, a heterodimer of 86- and 70-kD proteins, is a nuclear DNA-binding autoantigen. However, hydrophobicity analysis of the deduced amino acid sequence of the 70-kD protein had strongly suggested that this might also be a membrane protein. In the present study, using antibodies to synthetic peptides and a polyclonal antiserum to the purified protein, we show that the 70-kD protein of the Ku complex is present in isolated plasma membranes of human cells. By indirect immunofluorescence microscopy and fluorescein-activated cell sorting, we demonstrate that this autoantigen is exposed on the cell surface. In addition, we have identified several domains of the protein that are exposed. Our study provides one of the first demonstrations of a eukaryotic, nuclear DNA-binding protein that is also on the cell membrane. Moreover, our results might help explain how autoantibodies to the Ku autoantigen could target cells for an autoimmune attack.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=296862Documentos Relacionados
- A DNA-binding activity, TRAC, specific for the TRA element of the transferrin receptor gene copurifies with the Ku autoantigen.
- Islet cell autoantigen 69 kD (ICA69). Molecular cloning and characterization of a novel diabetes-associated autoantigen.
- Suppression of heat-induced hsp70 expression by the 70-kDa subunit of the human Ku autoantigen.
- Molecular definition and sequence motifs of the 52-kD component of human SS-A/Ro autoantigen.
- Isolation and characterization of a cDNA clone encoding the 60-kD component of the human SS-A/Ro ribonucleoprotein autoantigen.