The Toll-interacting protein (Tollip) is a negative regula-tor of the Toll-like receptor (TLR)-mediated inflammation response. Tollip is a modular protein that contains an N-terminal Tom1-binding domain (TBD), a central conserved domain 2 (C2), and a C-terminal coupling of ubiquitin to endoplasmic reticulum degradation (CUE) domain. Here, we report the sequence-specific backbone 1H, 15N, and 13C assignments of the human Tollip CUE domain. The CUE domain was found to be a stable dimer as determined by size-exclusion chromatography and molecular cross-linking studies. Analysis of the backbone chemical shift data indicated that the CUE domain exhibits three helical elements corresponding to 52% of the protein backbone. Circular dichroism spectrum analysis confirmed the helical nature of this domain. Comparison of the location of these helical regions with those reported for yeast CUE domains suggest differences in length for all helical elements. We expect the structural analysis presented here will be the foundation for future studies on the biological significance of the Tollip CUE domain, its molecular inte-ractions, and the mechanisms that modulate its function during the inflammatory response.

Keywords: CUE domain, innate immunity, NMR spectroscopy, resonance assignments, Tollip, Toll-like receptor