BOVINE GLYCOGENOSIS TYPE-II - THE MOLECULAR DEFECT IN SHORTHORN CATTLE

The molecular defect in Shorthorn cattle affected with glycogenosis ty pe II was studied. Polyclonal and monoclonal antibodies specific for b ovine skeletal muscle acid alpha-glucosidase were raised and used to s tudy the molecular and biochemical defect in seven affected animals. C ultured normal bovine fibroblasts pulsed and chased with [H-3] leucine produced a 130 kDa precursor form of acid alpha-glucosidase which was processed via several 100 kDa intermediate forms to the 65 kDa mature form within 26 h. Fibroblasts from affected animals were labelled in vitro and were shown to produce a cross-reactive protein which was ide ntified as the precursor form of the enzyme. The mature form of the en zyme was not found. The precursor form of the enzyme was demonstrated in Western blots of muscle tissue extracts from affected animals. Glyc ogenosis type II in Shorthorn and Brahman cattle must be caused by a d ifferent, independent mutation, since Brahman cattle lack the cross-re active protein for acid alpha-glucosidase.