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antifungal protein ginkbilobin-2-like domains found in plants This family includes the antifungal protein ginkbilobin found in seeds of Ginkgo biloba. The full-length protein contains a signal peptide and is called ginkbilobin-2 (Gnk2 or stress-antifungal domain). Gnk2 is an extracellular domain harboring a conserved cysteine motif (C-8X-C-2X-C) in its core. This domain is present in three types of plant proteins: cysteine-rich receptor-like secreted proteins (CRRSPs), cysteine-rich receptor-like kinase (CRKs), and plasmodesmata-localized proteins (PDLPs). Gnk2 from Ginkgo biloba and maize AFP1 CRRSPs have been shown to bind mannose. CRKs that typically have two Gnk2 domains in the extracellular region, form part of a large subgroup of receptor-like protein kinases (RLKs) in plants and have been shown to participate in the control of stress responses and development in Arabidopsis. PDLPs contain two Gnk2 domains in their extracellular region and a transmembrane helix, but lack a kinase domain; they associate with plasmodesmata and are involved in symplastic intercellular signaling, pathogen response, systemic signaling, control of callose deposition and are targets for viral movement proteins. No ligand have been identified for PDLPs and CRKs. Although the precise biochemical functions of plant Gnk2 are not known, the conserved C-8X-C-2X-C motif may point to carbohydrate binding, similar to G. biloba Gnk2 inhibiting the growth of several fungi by binding mannose moieties of the fungal cell walls. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",