Defective GAA does not hydrolyze lysosomal glycogen

Stable Identifier
Reaction [transition]
Homo sapiens
Defective GAA does not hydrolyze alpha(1,6) linkages in lysosomal glycogen, Defective GAA does not hydrolyze alpha(1,4) linkages in lysosomal glycogen
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Normally, lysosomal alpha-glucosidase (GAA) catalyzes the hydrolysis of alpha(1,4) and alpha(1,6) linkages in glycogen, yielding free glucose and shortened glycogen polymers. A wide variety of GAA mutations reduce or eliminate this catalytic activity, leading to glycogen accumulation in lysosomes. The two missense mutant alleles annotated here encode GAA variants with little or no activity and are associated with the infantile form of the disease (early onset with multiple tissues involved) (Brown et al. 1970; Hermans et al. 1991; Zhong et al. 1991). The defect primarily affects skeletal and cardiac muscle, so the disease event is annotated here as a failure of processing of the muscle (GYG1) form of glycogen.
Literature References
PubMed ID Title Journal Year
8420990 Structural and functional changes of lysosomal acid alpha-glucosidase during intracellular transport and maturation

Kroos, MA, Reuser, AJ, van Beeumen, J, Hermans, MM, Wisselaar, HA

J. Biol. Chem. 1993
5264799 Simultaneous absence of alpha-1,4-glucosidase and alpha-1,6-glucosidase activities (pH 4) in tissues of children with type II glycogen storage disease

Brown, BI, Jeffrey, PL, Brown, DH

Biochemistry 1970
3049072 Primary structure and processing of lysosomal alpha-glucosidase; homology with the intestinal sucrase-isomaltase complex

Kroos, MA, Reuser, AJ, van Beeumen, J, Oostra, BA, Hoogeveen-Westerveld, M, Hoefsloot, LH

EMBO J. 1988
Catalyst Activity

alpha-glucosidase activity of GAA mutants [lysosomal lumen]

Normal reaction
Functional status

Loss of function of GAA mutants [lysosomal lumen]

Name Identifier Synonyms
glycogen storage disease II DOID:2752 Lysosomal alpha-1,4-glucosidase deficiency (disorder), deficiency of glucoamylase, glycogen storage disease type II, acid maltase deficiency, deficiency of maltase, Glycogen storage disease, type II (disorder), Pompe's disease, Generalized glycogenosis (disorder), Glycogenosis, type 2
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