Laforin protein tyrosine phosphatase, N-terminal CBM20 (carbohydrate-binding module, family 20) domain. Laforin, encoded by the EPM2A gene, is a dual-specificity phosphatase that dephosphorylates complex carbohydrates. Mutations in the gene encoding laforin result in Lafora disease, a fatal autosomal recessive neurodegenerative disorder characterized by the presence of intracellular deposits of insoluble, abnormally branched, glycogen-like polymers, known as Lafora bodies, in neurons, muscle, liver, and other tissues. The molecular basis for the formation of these Lafora bodies is unknown. Laforin is one of the only phosphatases that contains a carbohydrate-binding module. The CBM20 domain is found in a large number of starch degrading enzymes including alpha-amylase, beta-amylase, glucoamylase, and CGTase (cyclodextrin glucanotransferase). CBM20 is also present in proteins that have a regulatory role in starch metabolism in plants (e.g. alpha-amylase) or glycogen metabolism in mammals (e.g. laforin). CBM20 folds as an antiparallel beta-barrel structure with two starch binding sites. These two sites are thought to differ functionally with site 1 acting as the initial starch recognition site and site 2 involved in the specific recognition of appropriate regions of starch.