a phosphate monoester + H2O = an alcohol + phosphate Binds 1 Mg(2+) ion. Binds 2 Zn(2+) ions. Isozymes 1 and 3 are a dimer of identical chains, isozyme 2 is a dimer of heterogeneous chains, one of each of the subunits from isozymes 1 and 3. Belongs to the alkaline phosphatase family.