Glycoside hydrolase involved in the hydrolysis of xylan, a major plant cell wall hemicellulose made up of 1,4-beta-linked D-xylopyranose residues. Catalyzes the endohydrolysis of the main-chain 1,4-beta-glycosidic bonds connecting the xylose subunits yielding various xylooligosaccharides and xylose. Endohydrolysis of (1->4)-beta-D-xylosidic linkages in xylans. Optimum pH is 4-6. Optimum temperature is 60 degrees Celsius. Glycan degradation; xylan degradation. Induced by D-xylose, dependent on the cellulase and xylanase regulator xyr1. Repressed by glucose through negative regulation by the crabon catabolite repressor cre1. Glycosylated. Belongs to the glycosyl hydrolase 11 (cellulase G) family.