From Proteopedia

Doppel (Dpl), named for downstream prion protein like^[1], is a homolog of the prion protein (PrP). It is a cell surface glycoprotein.

Structure of Dpl

spinqualitylabelsall models PDB ID 1lg4 Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image
1lg4, 20 NMR models ()
Gene:	Prnd (Homo sapiens)
Related:	1i17
Structural annotation: Resources: CATH : 1Lg4A00 InterPro : Ipr000817 Pfam : PF00377 SCOP : d1lg4a_ UniProt : Q9UKY0
Functional annotation: Cellular component: membrane Biological process: protein homooligomerization Molecular function: GPI anchor binding
Evolutionary conservation: Toggle Conservation Colors: Rows = identical sequences: Further Information: Caveats, Explanation, Complete Results at ConSurfDB
Resources:	FirstGlance, OCA, RCSB, PDBsum
Coordinates:	save as pdb, mmCIF, xml

Dpl has the same fold as PrP, with three alpha helices and two short beta strands, however it differs in that the third helix has a significant kink in it and it also contains two disulphide bonds.

References

Moore et al. (1999) Ataxia in Prion Protein (PrP)-deficient Mice is Associated with Upregulation of the Novel PrP-like Protein Doppel J. Mol. Biol. 292, 797-817