Extraction of gastric parietal cell autoantigen.

The distribution of gastric parietal cell autoantigen in subcellular fractions of bovine abomasum mucosa has been assessed by the capacity to neutralize antigastric parietal cell activity of pernicious anaemia serum. By far the greater proportion of the antigenic activity was in the microsomal fraction. Active material was soluble in 6 M-urea, pH 7·3. Removal of urea by dialysis produced an active suspension which on centrifuging gave an active sediment and an inactive supernatant. Electronmicroscopic and ultraviolet absorption evidence suggests that the antigenic component(s) of the microsomal fraction is associated with the smooth membranes and not with the ribosomes.