Glycogen branching enzyme, involved in glycogen accumulation; contains carbohydrate-remodeling activity that attaches a linear chain of α-1,4 linked linear chains to an interior glucose residue via an α-1,6 linkage; localizes to the cytoplasm in a punctate pattern; relocalizes from nucleus to cytoplasmic foci upon DNA replication stress; glycogen accumulation defect of the null mutant is complemented by human GBE1, which is associated with glycogen storage disease