Probably a non-catalytic chitinase-like protein, which binds to insoluble chitin and enhances the activity of the catalytic chitinases. Has weak chitin-binding activity. Expressed in the upper digestive tract. Staining is observed in the ventriculus, and in very rare individuals, also in the intestine or esophagus. No expression in fecal pellets neither inside the rectum nor defecated outside of the body. Causes an allergic reaction in human. Natural protein binds to IgE in 54% of the 24 patients from the Western USA tested allergic to American house dust mite (HDM). Causes an allergic reaction in dog. Natural protein binds to IgE in 57% of the 21 dogs with atopic dermatitis tested allergic to American HDM. In the intradermal tests, the natural protein produces positive reactions in 37% of the 19 dogs with atopic dermatitis tested allergic to American HDM. Binds to IgE in 77% of the 35 dogs with putative atopic dermatitis tested allergic to American HDM. Belongs to the glycosyl hydrolase 18 family. Chitinase class II subfamily. Although it belongs to the glycosyl hydrolase 18 family, Ser-148 is present instead of the conserved Glu which is an active site residue. Therefore this protein may lack chitinase activity.