Has both folate hydrolase and N-acetylated-alpha-linked-acidic dipeptidase (NAALADase) activity (By similarity). Also exhibits a dipeptidyl-peptidase IV type activity (By similarity). Release of an unsubstituted, C-terminal glutamyl residue, typically from Ac-Asp-Glu or folylpoly-gamma-glutamates. Binds 2 Zn(2+) ions per subunit. Required for NAALADase activity. Belongs to the peptidase M28 family. M28B subfamily.