The function of the domains of Trichoderma reesei endoglucanase I (EGI) has been studied. Truncated EGI proteins were expressed from the 3′-end deleted cDNAs in the yeast Saccharomyces cerevisiae under the control of the ADCI expression cassette. EGI protein was detected by monoclonal antibody EI-2 and EGI activity as cleared zones around growing colonies on agar plates containing hydroxyethylcellulose (HEC) covalently stained with Ostazin brilliant red (OBR). The results showed that the Thr—Ser-rich hinge region and the conserved ‘tail’ are not necessary for the efficient synthesis and secretion of EGI in yeast, but the intact core region is necessary for the enzymatic activity.
