Immunological properties of the XXXX @entity7860 target antigen.

@entity1 @entity7432 @entity11 @entity2097 @entity7860 @entity291 @entity214
The globular domain NC1 of @entity1 basement membrane collagen IV was isolated from glomerular basement membrane after collagenase digestion by chromatographic purification. The @entity1 NC1 appears as a hexamer of 160 kD by molecular sieve chromatography which migrates as a single molecule at gel electrophoresis without @entity214 ( @entity214 ). Reversible dissociation of the hexamer into monomers and dimers was achieved by 6 M @entity2097 - @entity7432 , @entity214 , or at pH values less than 4.0. All the subunits of 26 kD, 28 kD, 44 kD, and 50 kD showed reactivity with anti- @entity11 antibodies on immunoblotting. Inhibition-ELISA demonstrated that the intact hexamer also binds to anti- @entity11 antibodies at higher NC1 concentrations. However, dose-response curves indicated an approximately 20-50-fold increase in reactivity after dissociation of the hexamer in 6 M @entity2097 - @entity7432 . Analysis of thermostability demonstrated that heating for 24 h at 37 degrees C or 56 degrees C did not alter the reactivity to anti- @entity11 antibodies, while reactivity was lost after heating for more than 120 min at 95 degrees C. In contrast to @entity291 NC1 unfolding of the antigen occurs immediately and does not require elevated temperature. Rotary shadowing of @entity1 NC1 at neutral pH revealed homogeneous globules. Distinct but incomplete dissociation into monomers and dimers could be observed at pH 2.5. These in vitro data of the @entity1 NC1 domain give further evidence that most of the @entity7860 epitopes are sequestered within the NC1 hexamer and support the hypothesis that production of anti- @entity11 autoantibodies may be initiated after dissociation of the hexamer has been induced, possibly by a toxic or infective episode.
