InterPro2GO mappings assign chitin binding (IPR001002/IPR018371/IPR036861), chitin catabolic process and cell wall macromolecule catabolic process (IPR000726), and carbohydrate metabolic process (IPR016283, Glyco_hydro_19) to CHIB.

EC2GO maps EC 3.2.1.14 (the endochitinase EC annotated to CHIB) to endochitinase activity (GO:0008843).

Curator ISS transfer from the maize endochitinase A ortholog (UniProtKB:P29022) assigns extracellular region and endochitinase activity to CHIB.

SwissProt keyword-derived (SPKW) annotations present in the Sept 2025 goa_uniprot_gcrp snapshot but removed from the current GOA release after GOA retired the keyword2GO pipeline for cellular organisms.

For CHIB, the keyword "Plant defense" mapped to the generic "defense response" and "Polysaccharide degradation"/"Chitin degradation" mapped to "polysaccharide catabolic process"; both are correct-but-generic relative to the gene's specific antifungal and chitin-catabolic biology, which is captured by retained current-GOA terms and by the proposed more specific terms.

The UniProt "Secreted" subcellular location maps to extracellular region (GO:0005576), consistent with CHIB's signal peptide and secretory deployment.

Combined automated IEA methods (ARBA/InterPro) assign chitinase activity (GO:0004568) to CHIB, consistent with its GH19 / EC 3.2.1.14 endochitinase identity.

CHIB (P29023; ChitB / seed chitinase B; gene model GRMZM2G005633) is a maize GH19 plant endochitinase (EC 3.2.1.14) that hydrolyzes the beta-1,4 glycosidic linkages of chitin, a polymer of N-acetylglucosamine that is a key structural component of fungal cell walls and arthropod exoskeletons.

GH19 chitinases use a single-step inverting mechanism in a wide active-site cleft of an alpha-helical bilobed fold; chitin-binding modules enhance activity on insoluble chitin (the biologically relevant fungal-cell-wall form) and contribute to antifungal effectiveness.

CHIB is predicted to contain a signal peptide, an N-terminal chitin-binding domain and a catalytic domain (~281-282 aa, ~29 kDa), consistent with secretion to the apoplast/extracellular space.

ChiB/CHIB transcript abundance increases dramatically (~10-fold) in response to mechanical wounding and fall-armyworm (Spodoptera frugiperda) feeding, placing CHIB within plant defense signaling; ChiB shows highest expression in seed among surveyed organs and maps to chromosome 10 near insect-resistance QTL.

Direct CHIB-specific kinetic constants were not available in the retrieved corpus; function is inferred from EC 3.2.1.14 / GH19 assignment and supported by herbivory-induction and seed/pathogenesis-related-chitinase context.