Members of this protein family are biofilm-forming enzymes that polymerize N-acetyl-D-glucosamine residues in beta(1,6) linkage. One named members is IcaA (intercellular adhesin protein A), an enzyme that acts (with aid of subunit IcaD) in Polysaccharide Intercellular Adhesin (PIA) biosynthesis in Staphylococcus epidermis). The homologous member in E. coli is designated PgaC. Members are often encoded next to a polysaccharide deacetylase and involved in biofilm formation. Note that chitin, although also made from N-acetylglucosamine, is formed with beta-1,4 linkages.
Jiyao W et al.(2023). "The conserved domain database in 2023.",