Abstract
Two components of the cellulase complex (E.C. 3.2.1.4) of the fungus Trichoderma reesei were localized at the ultrastructural level. Immunocytochemistry and enzyme cytochemistry demonstrated that cellobiohydrolase and beta-1,4 glucanase were localized within cisternae of endoplasmic reticulum and within membrane complexes of cellulose-grown hyphae. Both enzymes were also present in the culture medium. Glucose-grown control hyphae lacked enzyme-specific staining, and no enzyme activity was detected in the growth medium.