The N-terminal domain of CelA codes for an endoglucanase activity on carboxymethylcellulose. The C-terminal domain probably acts synergistically to hydrolyze crystalline cellulose. Endohydrolysis of (1->4)-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. The linker region (also termed 'hinge') may be a potential site for proteolysis. In the C-terminal section; belongs to the glycosyl hydrolase 48 (cellulase L) family. In the N-terminal section; belongs to the glycosyl hydrolase 9 (cellulase E) family.