Cell surface expression of the 70-kD component of Ku, a DNA-binding nuclear autoantigen

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 synthet...

Full description

Saved in:
Bibliographic Details
Published in:The Journal of clinical investigation 1990-10, Vol.86 (4), p.1301-1305
Main Authors: PRABHAKAR, B. S, ALLAWAY, G. P, JAVARAIAH SRINIVASAPPA, NOTKINS, A. L
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Antigens, Nuclear
Antigens, Surface - analysis
Antigens, Surface - physiology
autoantigens
Autoantigens - analysis
autoimmune diseases
Biological and medical sciences
Cell Membrane - immunology
DNA Helicases
DNA-Binding Proteins - analysis
DNA-Binding Proteins - physiology
HeLa Cells - immunology
Humans
Immunopathology
Ku Autoantigen
Medical sciences
membrane proteins
Molecular Sequence Data
plasma membranes
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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.
ISSN:0021-9738
1558-8238
DOI:10.1172/jci114838