Glycogen debranching enzyme at Duke University suggest that the human AGL gene contains at minimum 2 promotor regions, sites where the transcription of the gene begins, that result in differential expression of isoform, different forms of the same protein, mRNAs in a manner that is specific for different tissues. When GDE activity is compromised, the body cannot effectively release stored glycogen, type III Glycogen Storage Disease (debrancher deficiency), an autosomal recessive disorder, can result. In GSD III glycogen breakdown is incomplete and there is accumulation of abnormal glycogen with short outer branches. Most patients exhibit GDE defiency in both liver and muscle (TypeIIIa),
Glycogen synthase asymmetric form, glycogen synthase is found as a dimer, whose monomers are composed of two Rossmann-fold domains. This structural property, among others, is shared with related enzymes, such as glycogen phosphorylase and other glycosyltransferases of the GT-B superfamily. Nonetheless, a more recent characterization of the "Saccharomyces cerevisiae" (yeast) glycogen synthase crystal structure reveals that the dimers may actually interact to form a tetramer. Specifically, The inter-subunit interactions are mediated by the α15/16 helix pairs, forming allosteric sites between subunits in one combination of dimers and active sites between subunits in the other combination of dimers. Since the structure of eukaryotic