| Domain | Location / identifier in Q6YYC5 | Known function inferred from domain family literature | Key structural features | Binding partners / activities reported for related proteins |
|---|---|---|---|---|
| RING finger zinc-binding domain | Znf_RING; InterPro IPR001841 | Strongly supports classification as an E3 ubiquitin ligase catalytic module. In rice and Arabidopsis, RING/RGLG proteins mediate transfer of ubiquitin from E2 enzymes to specific substrate proteins and thereby regulate protein stability, signaling, immunity, stress responses, and development (pqac-00000004, pqac-00000008, pqac-00000009). | Canonical RING domain is a cysteine/histidine-rich zinc-binding fold characteristic of RING E3 ligases; this domain confers ligase activity rather than protease or transporter function. In RGLG proteins it is typically positioned toward the C terminus (pqac-00000004, pqac-00000009). | Related rice RING/RGLG proteins ubiquitinate specific targets: OsRGLG6 ubiquitinates OsOTUB1 for proteasome-mediated degradation; OsRF1 ubiquitinates OsPP2C09; OsRGLG5 is reported as an immune-related RGLG ligase in rice (pqac-00000004, pqac-00000009, pqac-00000008). |
| von Willebrand factor A / vWA domain | VWF_A; InterPro IPR002035; vWFA_dom_sf; InterPro IPR036465 | In RGLG proteins, the N-terminal vWA domain is associated with protein-protein interaction and substrate recognition; more broadly, vWA domains often participate in assembly of multiprotein complexes and can bind divalent cations in some proteins (pqac-00000004, pqac-00000007). | vWA domains generally comprise ~200 residues and adopt a Rossmann-like α/β sandwich fold; many contain a MIDAS-like metal-ion-dependent adhesion site or related cation-binding capacity. In copine/BON1, the vWA domain shows a characteristic Rossmann fold and a Ca2+-binding site; in OsRGLG6, the vWA domain is specifically described as a conserved domain mediating protein-protein interactions (pqac-00000007, pqac-00000006, pqac-00000004). | In related proteins, vWA domains contribute to interaction specificity. BON1 vWA interacts with partner proteins such as BAP1/BAP2 and contributes to membrane-associated signaling functions; OsRGLG6 uses its overall domain architecture, including vWA, in interacting with OsOTUB1 (pqac-00000006, pqac-00000004). |
| Copine_C / E3_ligase-Copine related region | Copine_C; InterPro IPR010734; E3_ligase/Copine_domain; InterPro IPR052079 | This annotation suggests similarity to copine-family C-terminal modules and supports a membrane/signaling adaptor interpretation in addition to ubiquitin-ligase function. Copine-family proteins are calcium-dependent phospholipid membrane-binding regulators involved in immunity, development, osmotic stress responses, brassinosteroid signaling, and Ca2+ homeostasis (pqac-00000006, pqac-00000005). | Classical copines contain two N-terminal C2 domains followed by a C-terminal vWA domain; they are plasma-membrane-associated, calcium-responsive proteins. BON1 structure shows C2A, C2B, and vWA domains arranged in a conserved copine architecture, with Ca2+-binding features and phospholipid-binding capacity (pqac-00000006, pqac-00000007, pqac-00000005). Q6YYC5 lacks a classical full copine annotation in UniProt but the Copine_C hit suggests structural/functional resemblance within this broader membrane-signaling module family. | Copine proteins bind membranes in a Ca2+-dependent manner and interact with signaling proteins. BON1 directly regulates plasma membrane Ca2+ pumps ACA8/ACA10, interacts with immune/developmental regulators, and in rice OsBON1/OsBON3 act as suppressors of broad-spectrum disease resistance with stimulus-dependent relocalization (pqac-00000005, pqac-00000006). |
| Integrated architecture of Q6YYC5 | Combination of IPR001841 + IPR002035/IPR036465 + IPR010734/IPR052079 | The combined architecture most strongly supports that Q6YYC5 is an uncharacterized RGLG-like ubiquitin E3 ligase that probably functions in signaling-regulated protein ubiquitination, with substrate recognition/scaffolding via vWA-like regions and possible membrane- or Ca2+-responsive behavior suggested by the copine-related annotation (pqac-00000004, pqac-00000008, pqac-00000005). | Related rice RGLG proteins are described as containing an N-terminal vWA domain and a C-terminal RING domain and localize to cytoplasm and endoplasmic reticulum; copine-family structural studies indicate how Ca2+-responsive membrane association could be coupled to protein interaction modules (pqac-00000004, pqac-00000006, pqac-00000007). | No direct substrate has been reported for Os08g0135400/Q6YYC5 itself. By analogy to characterized rice RGLGs, plausible activities include E2-dependent ubiquitin transfer to signaling regulators; known substrates of related rice RGLG/RING proteins include OsOTUB1 and OsPP2C09, while related family members regulate immune, drought, ABA, and developmental pathways (pqac-00000004, pqac-00000009, pqac-00000008). |


*Table: This table summarizes the domain architecture of rice Q6YYC5/Os08g0135400 using the UniProt/InterPro annotations and maps each domain to experimentally supported functions from related RGLG and copine-family proteins. It is useful for inferring likely molecular function despite the lack of direct literature on this specific rice protein.*