title: The cytoplasmic domain of the T-cell receptor zeta subunit does not form disordered dimers.
abstract: Intrinsically disordered regions in proteins play active roles in recognition, signaling and molecular sorting. They often undergo coupled folding and binding giving rise to largely ordered interfaces with their binding partners. The cytoplasmic region of the T-cell receptor zeta subunit (ζcyt) has been previously proposed to specifically dimerize in the absence of a disorder-to-order transition, suggesting an intriguing dimerization mechanism that may involve multiple transient interfaces. We show here using analytical ultracentrifugation, NMR, size-exclusion chromatography (SEC) and multi-angle light scattering that neither ζcyt nor the cytoplasmic region of CD3ε significantly populates a dimeric state but that they are mostly monomers in solution up to millimolar concentrations. They experience a salt- and concentration-dependent shift of their elution volume in SEC previously interpreted as dimerization. Our data show that ζcyt does not form a highly disordered protein complex and leaves open the question as to whether completely disordered dimers (or other oligomers) exist in nature.
authors.affiliation: Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, MS 311, Memphis, TN 38105, USA. Electronic address: amanda.nourse@stjude.org.
authors.forename: Amanda
authors.initials: A
authors.lastname: Nourse
authors.affiliation: Structural Biology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, MS 311, Memphis, TN 38105, USA. Electronic address: tanja.mittag@stjude.org.
authors.forename: Tanja
authors.initials: T
authors.lastname: Mittag
mesh_terms: D002850:Chromatography, Gel; D009682:Magnetic Resonance Spectroscopy; D055503:Protein Multimerization; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000378:metabolism*; D013059:Spectrum Analysis, Raman; D014461:Ultracentrifugation
chemical_list: D011948:Receptors, Antigen, T-Cell; C054979:antigen T cell receptor, zeta chain
keywords: AUC; EDTA; HSQC; IDP; M; MALS; PRE; SE; SEC; SV; analytical ultracentrifugation; ethylenediaminetetraacetic acid; fuzzy complex; heteronuclear single quantum coherence; immune receptor; intrinsically disordered protein; molecular mass; multi-angle light scattering; paramagnetic relaxation enhancement; sedimentation equilibrium; sedimentation velocity; size-exclusion chromatography