Has a role in cell wall biosynthesis where it is involved in maintaining cell wall strength and shape. Endohydrolysis of (1->4)-alpha-D-glucosidic linkages in polysaccharides containing three or more (1->4)-alpha-linked D-glucose units. Binds 2 calcium ions per subunit. Calcium is inhibitory at high concentrations. N-glycosylated. Belongs to the glycosyl hydrolase 13 family.