This superfamily represents a structural domain with a core 3-layer alpha/beta/alpha structure, which can sometimes contain additional subdomains (also covered by this entry). These domains form the core domain of alkaline phosphatases. This structural domain is found in:Alkaline phosphatase ; most use zinc and magnesium as cofactors.Arylsulphatase (has an additional C-terminal alpha+beta subdomain) .Phosphoglycerate mutase (catalytic domain) .Phosphonoacetate hydrolase (contains an alpha+beta subdomain inserted near C terminus) ; uses zinc as a cofactor.Phosphoenolmutase .