This family of glycosyl hydrolases contains vacuolar acid trehalase and maltose phosphorylase.Maltose phosphorylase (MP) is a dimeric enzyme that catalyses the conversion of maltose and inorganic phosphate into beta-D-glucose-1-phosphate and glucose. This domain is believed to be essential for catalytic activity [1] although its precise function remains unknown.

1: Crystal structure of maltose phosphorylase from Lactobacillus brevis: unexpected evolutionary relationship with glucoamylases. Egloff MP, Uppenberg J, Haalck L, van Tilbeurgh H; Structure (Camb) 2001;9:689-697. PMID:11587643