Involved in cell wall degradation. Degrades polysaccharides containing beta-(1-->4)-linked galactans, acting as an exo-(1-->4)-beta-D-galactanase (By similarity). Hydrolysis of terminal non-reducing beta-D-galactose residues in beta-D-galactosides. Heterodimer of a large and a small subunit. The small subunit is N-glycosylated. There are three forms of the large subunit which have the same sequence but differ in charge. There are four forms of the small subunit which have the same sequence but differ in charge. Belongs to the glycosyl hydrolase 35 family.