The present invention relates to cellulase variants which comprise a proteolysis-resistant binding region or linker for binding the cellulose-binding domain (CBD) and the catalytically active domain (CAD), and which also have greater cellulolytic activity. The invention also relates to a gene construct, a host cell and an enzyme composition comprising said variants. The invention further relates to a method for producing fermentable sugar and to a method for producing a bioproduct, such as bioethanol, from cellulose material with the cellulase variants, the host cell or the enzyme composition comprising said variants.
