Refined definition of the 56K and other autoantigens in the 50–60 kDa region |
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Authors: | G J M Pruijn B Božič F Schoute L A Rokeach W J van Venrooij |
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Institution: | (1) Department of Biochemistry, University of Nijmegen, P.O. Box 9101, NL 6500 HB Nijmegen, The Netherlands;(2) Department of Rheumatology, University Medical Centre, Ljubljana, Slovenia;(3) Department de Biochimie, Université de Montréal, Montréal, Canada |
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Abstract: | Alteration of the acrylamide: bisacrylamide ratio in the SDS-polyacrylamide gel used for Western blotting strongly improved the unambiguous detection of antibodies against 50–60 kDa autoantigens present in autoimmune patient sera. The relative migration of Ro 52, the 56K autoantigen and calreticulin increased with reduced acrylamide: bisacrylamide ratios in contrast to that of Ro60, La and Jo-1. These analyses indicated that these six autoantigens correspond to six distinct polypeptides.Further analyses using recombinant calreticulin showed that (i) the 56K autoantigen is neither identical nor related to calreticulin and (ii) calreticulin is not a Ro autoantigen.A series of experiments designed to better characterize the 56K autoantigen showed that (i) the antigen is not detectable in fixed cells, presumably due to masking of the epitopes; (ii) about equal amounts of the antigen were recovered in nuclear and cytoplasmic cell, fractions after enucleation of the cells; (iii) the 56K autoantigen is not stably associated with either RNA or other proteins.Abbreviations a-
anti-
- CaR
calreticulin
- NHS
normal human serum
- NRS
normal rabbit serum
- r
recombinant
- RA
rheumatoid arthritis
- SLE
systemic lupus erythematosus
- SS
Sjögren's syndrome |
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Keywords: | 56K autoantigen Autoimmunity Calreticulin Immunoblotting Sjö gren's syndrome Systemic Lupus erythematosus |
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