Laforin, isoform 9 (EPM2A)

Plays an important part in preventing glycogen hyperphosphorylation and the formation of insoluble aggregates, via its action as glycogen phosphatase, and by boosting the ubiquitination of proteins involved in glycogen metabolism via its interaction with the E3 ubiquitin ligase NHLRC1/malin. Shows strong phosphatase activity towards complex carbohydrates in vitro, avoiding glycogen hyperphosphorylation which is associated with reduced branching and formation of insoluble aggregates (PubMed:16901901, PubMed:23922729, PubMed:26231210, PubMed:25538239, PubMed:25544560).

Dephosphorylates phosphotyrosine and synthetic substrates, such as para- nitrophenylphosphate (pNPP), also has low action with phosphoserine and phosphothreonine substrates (in vitro) (PubMed:11001928, PubMed:11220751, PubMed:11739371, PubMed:14532330, PubMed:16971387, PubMed:18617530, PubMed:22036712, PubMed:23922729, PubMed:14722920). Forms a complex with NHLRC1/malin and HSP70, which inhibits the cellular toxicity of misfolded proteins by promoting their degradation through the ubiquitin-proteasome system (UPS).