dual specificity phosphatase domain of laforin and similar domains
This family is composed of glucan phosphatases including vertebrate dual specificity protein phosphatase laforin, also called lafora PTPase (LAFPTPase), and plant starch excess4 (SEX4). Laforin is a glycogen phosphatase; its gene is mutated in Lafora progressive myoclonus epilepsy or Lafora disease (LD), a fatal autosomal recessive neurodegenerative disorder characterized by the presence of progressive neurological deterioration, myoclonus, and epilepsy. One characteristic of LD is the accumulation of insoluble glucans. Laforin prevents LD by at least two mechanisms: by preventing hyperphosphorylation of glycogen by dephosphorylating it, allowing proper glycogen formation, and by promoting the ubiquitination of proteins involved in glycogen metabolism via its interaction with malin. Laforin contains an N-terminal CBM20 (carbohydrate-binding module, family 20) domain and a C-terminal catalytic dual specificity phosphatase (DSP) domain. Plant SEX4 regulate starch metabolism by selectively dephosphorylating glucose moieties within starch glucan chains. It contains an N-terminal catalytic DSP domain and a C-terminal Early (E) set domain.