Mature 98,000-dalton acid alpha-glucosidase is deficient in Japanese quails with acid maltase deficiency.

We compared acid alpha-glucosidase of acid maltase-deficient Japanese quails, an animal model of human late-onset glycogenosis type II, with that of normal controls. Antibody produced in a rabbit against acid alpha-glucosidase purified from chicken pectoral muscle cross-reacted with that of Japanese quails. The presence of a 110K and 98K form of acid alpha-glucosidase was confirmed in normal controls by immunoblotting. However the 98K form was absent in the affected quails. Subcellular distribution studies demonstrated that the 98K form, but not the 110K form, was localized in the lysosomes. This suggests that the 110K form is a precursor of the mature 98K form of acid alpha-glucosidase. In the affected quails, the 110K precursor is synthesized, but maturation to the 98K form does not occur or may be extremely deficient.