N-terminal double-psi beta-barrel fold domain of the expansin family and similar domains
The plant expansin family consists of four subfamilies, alpha-expansin (EXPA), beta-expansin (EXPB), expansin-like A (EXLA), and expansin-like B (EXLB). EXPA and EXPB display cell wall loosening activity and are involved in cell expansion and other developmental events during which cell wall modification occurs. EXPA proteins function more efficiently on dicotyledonous cell walls, whereas EXPB proteins exhibit specificity for the cell walls of monocotyledons. Expansins also affect environmental stress responses. Expansin family proteins contain an N-terminal domain (D1) homologous to the catalytic domain of glycoside hydrolase family 45 (GH45) proteins but with no hydrolytic activity, and a C-terminal domain (D2) homologous to group-2 grass pollen allergens. This family also includes GH45 endoglucanases from mollusks. This model represents the N-terminal domain of expansins and similar proteins, which adopts a double-psi beta-barrel (DPBB) fold.
Jiyao W et al.(2023). "The conserved domain database in 2023.",