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N-terminal double-psi beta-barrel fold domain of the alpha-expansin subfamily Alpha-expansins (EXPA, expansin-A) have cell wall loosening activity and are involved in cell expansion and other developmental events during which cell wall modification occurs. They also affect environmental stress responses. Arabidopsis thaliana EXPA1 is a cell wall modifying enzyme that controls the divisions marking lateral root initiation. Nicotiana tabacum EXPA4 positively regulates abiotic stress tolerance, and negatively regulates pathogen resistance. Wheat TaEXPA2 is involved in conferring cadmium tolerance. Alpha-expansins belong to the expansin family of proteins that 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 model represents the N-terminal domain of alpha-expansins, which adopts a double-psi beta-barrel (DPBB) fold. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",