This is a central domain of the eukaryotic variant of the glycogen debranching enzyme (GDE). The eukaryotic GDE performs two functions: 4-alpha-D-glucanotransferase, EC:2.4.1.25, and Amylo-alpha-1,6-glucosidase, EC:3.2.1.33, performed by the, respectively N- and C- terminal halves of eukaryotic GDE enzyme This central domain follows the glucanotransferase domain and precedes the glucosidase (GDE_N) domain. It is very likely that the current definition contains two or more domains, by analogy with bacterial GDEs, this domain should be involved in substrate- binding either for the N-terminal glucanotransferase and/or the the C-terminal glucosidase (or both).