Structural domains comprising this superfamily share the structure of the N-terminal domain of beta-1,3-glucan recognition proteins, also known as gram-negative bacteria-binding protein 3 (betaGRP/GNBP3), have specific affinity for beta 1,3-glucan, a component on the surface of fungi and bacteria. Beta-GRP is a biosensor protein that complexes with pathogen-associated beta-1,3-glucans and then transduces signals necessary for activation of an appropriate innate immune response. They are present in insects and lack all catalytic residues PMID:15610820,PMID:10827089.