AlphaFold Confidence Callout: Soluble Extracellular Domain mean pLDDT > 85.0. Flexible loop regions (UniProt residues 108–112 and 159–172) are modeled with moderate confidence (pLDDT 60–79), reflecting authentic conformational flexibility.

Binding Interfaces & Competitive Antagonism: Native Receptor (DcR3 / DR3): 22 contact residues (PDB 3K51, <4.0 Å) across cleft and loops. Therapeutic Neutralizing Epitope: 31 contact residues (DE loop & external face). Steric Overlap (Competition): Shared footprint at Arg103, Arg156, and loops 102–116 & 166–180 directly explains competitive receptor blockade.